Great news, this is untrue! I just took a look at this effect and can confirm that when Steelstar raised the proc rate, there were no other changes to effect availability as far as I can see. Quell was added to this effect suite in 2019 by yours truly during the Sharn development cycle before release, and since then there's been absolutely no changes beyond the proc rate increasing with U66.
Hi Tonquin, I had a couple thoughts on this -
First off, unfortunately Quell IS a very niche effect that is also not effective on bosses. Moreover, I cannot think of a single time I have seen this effect trigger on trash mobs, to greater effect than other cc. It might be different if the effect duration were made to be much longer, but in my experience by the time I'm hitting a divine caster, it's dead in seconds anyways. I don't think it adds any value to a weapon effect that can debuff a target in so much stronger ways.
Secondly, as it stands, any class I have seen use this effect cannot maintain more than one stack of Dust/Ash, and maybe 50% uptime on Ooze. Was the intention of the effect to be used in conjunction with 3+ other people to fully stack all debuffs? I'm not against coordinated play at all, but at that point it makes more sense for players to bring something from IoD and debuff that way.
I'm sure this topic has been touched on before, but with FoM raid loot having the effect revisited, I think a lot of players would like the "all-in-one debuffer" weapon effect to function as advertised, instead of having additional hoops to jump through and as much RNG involved making the effects actually stick.
Edit: Another alternative would be to keep the "rarity" of the effects, but to have them stackable or in some way unique to that weapon effect. Even something as simple as damage on hit, to keep pace with bone weapons that are outputting a ton more comparatively.