Knowing the enemy playstyle is a necessary evil. No way around it, because it's been fine-tuned for years. However, knowing how your champion interacts with Summon Aery, as an example, is not hard to figure out after one game, if you even need that game. They are very basic already, and don't need a 3-week tutorial to cover before you can even consider trying that OP Annie build you just saw last game, because you had the misfortune of facing one who passed the tutorial.
Even excluding all of that, there is little to no reason to hold back players who do not seek the help. As a universal example, you teach players in Chess how to do things, correct movement, en passant, how to castle, etc. However, that doesn't make it helpful to restrict a player from castling when the opponent gets to. If you want to intertwine players of different skill levels, they're going to need the same skills, or else you're setting up the new player for a bad experience, especially when they can't adjust to mimic that playstyle the following game.
Again, advice is good. Presets are good. Forcing is bad. When I am playing League of Legends, I expect to be playing the full game, just like everyone else. If I'm playing League of Legends Junior in a full-on LoL match, I'm probably going to get frustrated simply because I can't do the fun things I just saw some guy do. If I'm a relatively adjusted player due to playing a similar game (DotA 2, HoN, Smite), I'm gonna drop that game in heartbeat. That's just not fun for anybody.
Again, I used to coach these peeps. They were never that helpless to learn the game back in the day, and this was before the better tutorial came out. However, that could be for a variety of reasons. Many could be because even the movement tutorial was too hard/unfun for them. However, I promise you that forcing preset pages, as opposed to suggesting them, was not going to bring those folks back. They used those presets to a fault already, at least those that were willing to learn. The rest were frustrated with the appearance of a prescribed tutorial, and quit ahead of time.
There is literally no benefit to having a forced 10-level tutorial. Players that want to shove a playstyle can't experiment. Players who want to stay the course end up stomped by those that don't, and then can't adapt to it. It is backwards of Riot's main (and viable) philosophy, learn by playing. If you can't play that way, how do they expect you to learn about dealing with it? Keep in mind, there are 10 of 15 keystones that are unobtainable until level 10. That's a lot of coddling, and ultimately, no benefit.