Everyone doesn't have a smurf, most people play the game casually and even so, 25 million new active smurf accounts in just 2 years? These are also active not unique accounts IE they play regularly, I know a lot of people just make a smurf and never use it, hell I'm one of them. I'm not going to go surfing through Riot comments but I remember it being mentioned somewhere that most players don't have smurfs. Second of all, not many people get banned period, never mind permabanned once again the boards have disproportionate amount of permabanned people, you know what I mean? There's dozens of "Rito pls unban me I wasn't scripting I swear" posts per day, the boards are where people come to whine about that. Also, permabanned accounts don't count towards active accounts because they don't play. As for daily vs weekly, there's no statistic we have that can confirm or deny that but I'd say that the claim doesn't hold water since Riot's revenue was even more than last year (I believe 1.7 billion dollars) and it hasn't taken a dip in any year since the game's release. I would assume that people playing less often means less microtransactions but that could be because of the extra players so there's no way to confirm or deny the claim unless Riot releases new numbers. Finally, you've got to keep in mind that most players probably didn't play daily to begin with since most people play the game pretty casually.
As for the dynamic queue thing, I didn't say that Reddit and the boards CAN'T be right, only that they don't represent anywhere close to the majority of players, just look at users, reddit has like~900,000 users (and that number doesn't have Active profiles accounted for) and the boards has far less than that. Now obviously 900,000 people is still a lot but when you're dealing with a game with 100 million players it isn't that big, it just objectively doesn't represent your average player, it also only really represents NA and EU when there are a lot of other servers and China for example has way more players than NA.
That's of course not to say Reddit can't be right, but taking something as broadly disapproved as Dynamic Queue isn't a good example. Of course it was bad and they bowed to Reddit in part because compared to normals, ranked isn't played by nearly as many people, it's played mainly by Veterans and hardcore players, just the demographic Reddit represents. Riot tried to incentivize more people to play ranked with Dynamic Queue but they went back on it when they realized it was both a failure and it undermined the competitive integrity of Ranked in general. Another example would be Reddit saying something like Ghostblade Lucian was really broken back when it first became a thing and it was in fact really oppressive and terrorized the game until they nerfed him into the ground, most players hated the fact that Lucian was that strong and was picked in like 30% of games with an absurd winrate so Riot nerfed him, that wasn't Reddit representing the whole community, that was it being broken and the community as a whole not liking it, which in no way proves that Reddit suddenly represents everyone. Of course Reddit gets it right pretty often and have influenced a lot of changes that most casual players wouldn't think about, most recently the Heartseeker Lucian splash and the Heartseeker Quinn ingame model, the best example of that sort of thing would be Riot pulling back the original god awful SKT skins and making new ones.
As for the validity of Riot's numbers, you're right in saying that we have no way of knowing because no one else has the capability to give accurate data, but we didn't have anyway of knowing back when they said 75 million and their Revenue numbers, esports gains, the fact that so many people actually consume league of legends content be it on Youtube or official Riot videos in the client and the multitude of other things I haven't thought about certainly support a game that's both massive and still growing.
If they were lying which they have done in the past, wouldn't it be kind of easy to expose by looking at other figures? I feel like that wouldn't be worth the risk and would destroy their reputation (believe it or not outside of Reddit and the boards they have a very good reputation) and it could totally destroy them as a company. Not to mention that if the game were failing why would they support just one single game for eight years without coming out with a new one, we only just started hearing about a new Riot game being in the works in 2015. I feel like we can trust them on the 100 million players data because of those factors. Sorry for the wall of text.