Conqueror hasn't fixed top lane. High tier players take Grasp against non-tanks still.

Conqueror kinda sucks, is inferior to Grasp (which is overpowered), shouldn't balanced around tanks, and is worthless in teamfights. Grasp outtrades it early by a large margin (which is why many high elo players go Grasp if they aren't against a tank that they need Conqueror to fight and outscales it with permanent health whereas Conqueror just becomes unusable in teamfights). Plus you can't take it jungle so Rhaast is out of a keystone still. (Also Conqueror refreshes with DoTs for some reason...)

Basically, Riot made Conqueror a bandaid fix to the tank issue while you can clearly see the issue still exist with Black Cleaver users, the worst users of Conqueror, are complete dogshit, especially those who relied on the high AD Fervor gave due to their high AD ratios that Conqueror does almost nothing for.

If Riot wants to fix the top lane issue, make Conqueror 10-55 AD, 10% true damage convert, charge up in 2 seconds against champions (if the stacking was initially started with a minion and then you strike a champion, you still need 4 seconds charge up. Basically, have the game check what began combat to choose the charge time), and have a 5 second duration (but no longer refresh with DoT effects).

Grasp should be nerfed to about 3% of your HP as damage, 1.5% healed, and gain 3 perma health (1 perma HP if ranged). You can give it the new 'type of combat' clause that I suggest for Conqueror to compensate a bit (though probably 3 seconds charge rather than 2 since healing percent health scales very strongly across the game with resistance stacking).

Make Cleaver 30% armor pen again and give it the Wit's End treatment if you're scared about ranged champions. Give Phage 5 AD because the item has been powercreeped out of being a viable rush.

Btw Riot wants a "proper solution" for shield stacking but somehow didn't give one for top lane.