There have been many points in time, most characteristically MoP and BfA, when non-organized players could get within one tier of the max ilvl of the game in most slots. I don't think we can argue that the raiding scene in MoP was dying or suffered because someone could get solid gear from Valor over months or that BfA suffered because people could turn WM on and conquest cap, getting a full set of high ilvl gear months into each tier.
I think the problem is that e.g. in Shadowlands, the best gear you can get is capped low and you can also get it extremely fast. You can get Cypher to max in 2-3 weeks and then gear up with Cypher gear within the week.
What MoP did right (BfA did it to but it never felt like they intended that for a casual progression path, even if it was the best casual progression path the game ever had) was give clear goals to more casual players which also took MONTHS to complete. Sure you could get Valor items for almost every slot that was just 1 tier below what raiders had but you would finish with that about 4 months into the tier. So it was not a problem for raiders since they could just use the system as a fall back for bad luck and it also meant non-raiders' ilvl took very long to get high enough to confuse PuGs.
I don't think Mythic should stop dropping gear personally. I can see some merit in the argument but ultimately I find that it doesn't really solve any issues. I do think Heroic raiding needs changes to the reward system (imo ilvl should upgrade by a tier in the Vault just like it does for M+; Heroic should give you a chance at a Mythic ilvl item OR neither should bring higher ilvl loot in the Vaultand M+ should get loot scaling all the way to +25 were it would reach Mythic raiding ilvls). But most importantly for the majority of the players, the gear progression for people not doing organized instanced content should not be something that you clear in 3-4 weeks at most. Imo you should be able to get to the normal level within maybe 6 weeks and slowly get to the Heroic ilvl well past the mid-point of the tier at 4-5 months. We have had systems like that before and I have not seen any evidence they made people quit raiding.
With Dragonflight reimagining crafting it should very much be possible to allow very slow but meaningful progression for all players. And if people's issue is that they cannot tell what other players can do from their ilvl, why the fuck are they looking at ilvl only??? Gearscore being crap was established well over a decade ago . . .