To clarify some terminology, common in gameplay boards
#Competitive or Dedicated?
Competitive: as good as or better than others of a comparable nature
A competitive player is one which is comparing themselves relative to other players. Including those that they might never face. While PvP has a natural degree of competitiveness associated with it on a per-match basis, you're only comparing yourself to all other players if you're playing ranked. So, competitive league players would be divided between ranked and unranked, because one is making the unnecessary comparison while the other is not.
Dedicated: devote (time, effort, or oneself) to a particular task or purpose
This has nothing to do with relative comparison to others. As such, simply spending many hours playing the game, in any game mode, would be considered dedicated.
I'm posting this, because i've seen people making both claims that "riot designs the game for competitive players" and "riot designs the game for casual players". Though, most arguments i've seen for the latter complaint, seem to be referencing dedication rather than competition. Which would include things like shorter games which favor the less dedicated player pool.
If i had to guess, a more accurate assessment would be that riot has focused their design around non-dedicated competitive players (E.g. Players who play a couple of games, of ranked, a week). So generally the more casual and dedicated you are towards the game, the less they're designing different systems around you. I'll just list two quick examples of incentives they've added to the game to promote this behavior, ranked end of season rewards and time/champion gated boxes.
Which makes a lot of sense, considering that they want to market the game as a competitive E-Sport, but they also need to keep in tune with the market, which has shifted towards more small form content, with the rise in popularity of mobile games and pressure from tencent. Even though, mobile games are completely tangential to a PC exclusive like league, market trends are still market trends.