To be honest even if you gave the entire casual base 425 pieces of gear right now, they still wouldn’t be able to clear mythic raids. Literally every top guild that clears a mythic raid never has bis gear when they do either.
But I still don’t agree that you should be given end game gear for doing casual game play when mythic raiders actually have the skill set, they put in the time/effort to find a guild/group and they’re competent enough to work as a team to down difficult content.
Mythic + spamming has kind of ruined gear in my opinion. It doesn’t matter as much anymore like it did back in vanilla. You used to go months without getting an ugprade, now you do 35 minutes of world quests and you get 4 pieces of loot then you complain about it not being 425 like it was that difficult to complete.