Maokai got reworked for being a generalist
And I agreed with the rework, Maokai was too good at everything and had no specific niche other than "need a tank? Pick me." But doesn't the same apply to Gragas? Galio was popular but that's simply because he was overtuned. But Gragas is literally Maokai 2.0 with an interesting ult. He poked hard in lane, has hard engage, has durability and has sustain. You literally can't kill Gragas unless he fucks up. Better still, he's also a tier 1 jungler in addition to being a tier 1 top laner.
What are the downsides to picking Gragas? He has everything. Like old Maokai, I don't find him overly oppressive in lane but you realize when playing against him, virtually every lane he plays is free because he's so safe. Maokai had conditional mobility, Gragas doesn't. And Maokai sustain required interaction, Gragas' doesn't. How come gragas isn't being looked at for violating the same things?
I don't even think Gragas is really OP or oppressive, I just can't fathom how he's allowed to exist in his current state when he's doing the exact same thing old Maokai did, but in many cases he does it better.