What you described is really the crux of it all.
The game is so complex and open ended that most average players cannot handle making and creating builds so they go with what is marketed to them by GGG or played by top streamers. It's no surprise the that this league has 35% Necromancers, the highest it has ever been despite being a niche and cumbersome playstyle. And Necromancers despite being super strong early game aren't going to be the best simply because they can't compete against something like a Headhunter Tornado Shot build when it comes to mapping.
I don't really think this is ever changing to be honest. This is probably the most balance league in that every Ascendancy is powerful, every playstyle is powerful and just about every skill is powerful. But players will rather follow other people than do something on their own and I can't blame them, there goes a lot into making a build.
IMO even though starting out following a build is fine, even maximizing these builds you need high knowledge of the game. Lots of dated and false information out there which can cause even bigger headaches. Having fundamental knowledge of the games core mechanics is essential for long term success.
And honestly... many streamers playing for 5 years+ still don't know enough. That's how indepth this game is. There is always something that you are missing. The best is to follow players who play certain archetypes across all leagues. Like DonTheCrown for melee, Grimro for speed clearing builds, Uber for summoners and Mathil for cheap but effective builds.
