Firstly, you're 100% correct, that being said, I don't think it has to be. Pokemon Unite, if it's remotely playable, will do well because it's goal isn't to beat DOTA2/LoL as a MOBA, it's goal is to turn young gamers and Pokemon fans into people who play MOBAs for the first time. It'll likely succeed because they aren't bothering with building and jungling is much more simple than it is in LoL, also it's so on theme that you find wild Pokemon in the tall grass.
As someone who only got into the MOBA genre very recently, and who only did so because 4 of my friends wanted to play and needed a 5th because nobody wanted to top, I was kept out of it for literal years because of how complicated it is. Streamers I love would swap to League or DOTA and I'd immediately turn it off because I just didn't understand how the game works. Gameplay depth is important, but in a genre where you need an excel spreadsheet in front of you at all times, Pokemon Unite won't succeed because of it's depth of play, it'll succeed because of it's simplicity in a drastically over complicated genre.
Pokemon Unite vs League/DOTA is a lot like Nintendo's console stance vs Microsoft and Sony. While the newest Playstation and Xbox consoles duke it out to see who's the better bad gaming PC, Nintendo just keeps making games that are fun for everyone and consoles that are accessible to all. My mom, who is 65, asked me about Pokemon Unite and how to do a MOBA today and I honestly believe she will download it and play it. My mom also bought a Switch and Animal Crossing after not having played/been around a video game/watched a game be played since probably 2003 when I lived at home and owned a Gamecube.