That’s how it works. Nerf content to make it less appealing and people will do it less.
People who don’t raid now are not raiding because they don’t want to raid. Make their content pointless and they’re not going to suddenly wake up on a mythic raiding team with decades of experience. They’ll be off looking for something fun to do.
I think most of the people who support the changes are the same posters who show up on every hot button topic involving controversial and unpopular changes to the game. A lot of them don’t even play the game. Hey, you’re posting on a classic character. Slow day? End game not keeping you busy?
Paid carries will now be done by mythic raiders, whose gear will be far better than anyone else’s. Anybody who is at gold cap on many characters would be tempted to make the conversion to hard cash. Mythic raiders would hardly be immune.