On the subject of Clash
Disclaimer: Obviously not a Riot employee, nor do I have any special knowledge of their plans/decision making. This is simply my analysis of the mode.
Ever since League was created, and really ever since multiplayer games/sports have been around, there has been a separation between "amateur" and "professional" - everyone knows this. What most people do not recognize is that there's more than simply these two categories of customer/player bases. As one example, take tennis. In tennis, you have people who go to the court simply to play with family/friends to relax. You have those who play in one or two USTA local tournaments per year. You have those who play in many tournaments each year, but aren't at the "major" tournaments and aren't ranked. And you have those who play professionally in major tournaments as their living.
In chess, you have similar groupings. In football, the same. Notice that there can be ranking systems that are not professional rankings. This is very important - it is possible to have ranking without it being a competitive ranking.
This is what League is. League of Legends, the base game (i.e. any game mode available in client), including ranked, is the "let me go hit the tennis ball with friends". Ranked itself is the "let me play in a couple tournaments per year just to see how I stack up against others". It is not a "serious" ranking system designed for competitive rewards/ability. It can't be - even in a forced "5 man premade" mode (which doesn't exist right now), the ability to continually change/alter your teammates to try and "game" the system and win more would ruin the competitive nature of the mode.
Many players like the game of League, but hate how normal modes are not "serious". They don't want to play ranked solo/duo and have to deal with 3-4 random players. They don't want to play ranked flex and have to go to the hassle of finding 4 others committed to multiple games. They want to play in a bracket where they compete for a "winner" position against other teams, and where people are committed to trying to do so. This is what gave rise to tournaments hosted by third parties - be they "in person" tournaments or online tournaments. Riot even supports in person third party ran tournaments themselves - even though they don't make money directly from them at all. They also support third-party online tournaments through sites such as battlefy and others if the owners of the tournaments apply properly for Riot support.
These are not "small" tournaments. While each individual tournament may be small, there is a very sizable playerbase who either only play in tournaments or mostly play in tournaments (i.e. only using "regular" League for practicing/scrims). Those players are also the same players who are not likely to be using the Boards - they don't need to be finding teams or discussing the game itself, because their only goal is to compete. This is similar to how your typical USTA tournament player doesn't actually ever provide any input about rules changes, etc. We simply get the magazine once every couple months and read to get updated, then say "welp, okay, these are the new rules/play/whatever".
Riot obviously knows how big this market is - they provide support to tournaments so they kinda have to. Obviously any business is going to want to capitalize on as many "segments" as they can - it's for this reason that airlines have everything from first class to premium economy to basic economy - because each product is designed for a different "market segment". Likewise, League of Legends has LCS/"professional" League for those players, but it also has "regular" ranked for your "average Joe" who just wants to see how they stack up, and lastly has normals for just your "go hit the ball with friends for a bit to relax" players. But what about your "amateur competitive" League players?
Currently (assuming you don't count Clash, as it's still in beta and not fully fleshed out yet) there is no game mode for "amateur competitive players". There is no mode where players can form a team, and compete in a tournament against other preformed teams - not one owned and operated by Riot. Riot is not getting money from third-party tournaments - but they can monetize a system like Clash. So now that we've defined the market segment Clash is designed for....
No, Riot is not going to make Clash "less competitive" simply because it doesn't suit you. Clash is not designed for "casual" players that are not willing to block out time and commit to playing in a tournament bracket. It is not designed for players who want "casual" changing of teams. Clash is designed as a tournament - meaning you form a team, and you play with that team. While substitutions would be helpful for some situations, they would be abused by some teams and decrease the competitive, tournament nature of the mode - meaning that no longer would it have the appeal for the market segment it's designed for.
If you don't like Clash, nobody says you have to play. Just how if you don't want to see how you rank against others, nobody forces you to play Ranked League. Many times people forget that not every player wants what they want from League - and Riot isn't making everything just for you. The boards have a very lopsided group of players from the "ranked" bracket - as compared to normal, "competitive amateurs", and professional players. The boards are not indicative of the proportion of the community that wants Clash the way it is. When posting about clash, remember to consider that just because it doesn't appeal to you does not mean it's "bad" or needs changed.