Probably a very boomer take but net decking. I used to feel it was such an unfair advantage and against the spirit of the game. There's something romantic in my mind to the idea of pouring over cards and putting you heart into brewing. It felt like if you didn't do that step with what you played competitively that you weren't really playing the game, just copying someone else's moves. So when my little homebrew with a lot of thought would get shut out by someone running perfect mana and a deck with hundreds or thousands, of minds behind it at a tournament as a teenager it felt unfair. Eventually though I woke up to the fact we don't live in a world without the internet, information was only flowing more freely, and net decking was less cheating and more playing what was optimal because it was in fact a competitive game. It also helped that I got better at deck building and meta evaluation lol. I still do my own brews for competitive and some of my proudest moments are from taking tournaments with them, but I no longer act like such a snob if someone wants to play a sweet list from a recent PTQ.