Support became more popular because it’s more like DPS. It’s not actually “support” that became more popular, they just changed the support design to be “DPS with utility”. Which I personally don’t like.
So yes, if you design tanks to be more like DPS, the role will become more popular. But it will also not be “tank”. It will be “beefy DPS”.
Is that a good thing to do? Idk, maybe for some people. But I don’t really like that because I play the game exactly because support was what it was. I don’t like playing “DPS with utility”, I like to play “support”. But sure, if you make every role more like DPS, more DPS players will play the other roles, but at the expense of people (me) who don’t like playing DPS.
Edit: But of course it can also be a net positive. Junker Queen, I think, is seen very positively by most tank players despite playing more like a traditional DPS character. So I’m not saying it’s bad to do that, I recognize that it can be positive and maybe I’m just the odd one out or maybe it’s better for tanks than it is for supports.