I feel like you didn't read what I said at all. First of all, it DOES have good bulk with only HP investment (doesn't die to a jolly 252 ice spinner tusk) especially when considering chip healing and protect. It's not enough bulk to beat hyper offensive mons, but that is something I addressed- since that is not where Gliscor is best. Gliscor works best as a mon to easily come in and knock boots off for its teammates which set up hazards and then it can set up an SD and sweep once everything is sufficiently chipped from hazards. Also, a lot of SD Gliscor sets sacrifice speed for extra bulk and it makes it even harder to kill for balance and bulky teams
Gliscor's bulk not being good enough for the HO matchup is a pretty big thing, meaning in those matchups, its not contributing much, if at all. When you want every pokemon on your team to contribute to every matchup, that is a big thing. Sure, gliscor can live a tusk ice spinner, but its doing 40-60% depending on tera, so its not immediately threatening it back. And that gliscor will be at pretty low health after the exchange if they don't decide to tera (which they really don't want to), so if you pressure it, it won't be able to recover as easily. And this is assuming its bulky, offensive struggles even more to take hits.
252 Atk Wellspring Mask Ogerpon-Wellspring Ivy Cudgel vs. 244 HP / 0 Def Gliscor: 306-362 (86.9 - 102.8%) -- 18.8% chance to OHKO
144+ SpA Slowking-Galar Ice Beam vs. 244 HP / 2 SpD Gliscor: 448-528 (127.2 - 150%) -- guaranteed OHKO
I will concede that g-weezing does beat gliscor, but knocking it off on one switch in goes a really long way with your other hazard setters. Furthermore, mola absolutely doesn't beat gliscor at all.
Molas job isn't to beat gliscor, its to take its hits, and get in a teammate. And that is completely fine. In this job, mola does well.
+2 12 Atk Tera Normal Gliscor Facade (140 BP) vs. 252 HP / 252+ Def Alomomola: 243-286 (45.5 - 53.5%) -- 37.1% chance to 2HKO
Mola in fact, is tanking that pretty well, and regenerating that off.
Tusk does beat a non-teraed gliscor for sure, but every single team has a tusk answer, and tusk gradually gets chipped down and can't heal.
Okay, so you try to out offense it before tusk is worn down too much, but that's what you should be doing in the gliscor MU.
Waterpon beats gliscor no question, but hates hazards, which gliscor is always paired with.
Well, you utilise your own hazard prevention techniques, which if you are using waterpon on balance, you will have. Something like tusk, treads, corv, geezing even talon will work well.
I don't think that there aren't answers to or ways to beat gliscor and never claimed that, but the point is that it puts a difficult strain in the builder because bulkier teams have very few ways of punishing or handling SD gliscor on a hazard stack.
But they do have multiple ways to beat SD Gliscor on hazard stack.
Alomomola
Corviknight
Darkrai
Dondozo
Dragapult
Dragonite
Gholdengo
Great Tusk
Iron Valiant
Kyurem
Landorus-T
Meowscarada
Moltres
Waterpon
Pecharunt
Primarina
Hamurott
Glowking (ice beam go brrr)
Ting Lu
Zamazenta
Zapdos
Weavile
Geezing
Latios
Keldeo
Washtom
Skarmory
Now, do all of these pokemon beat Gliscor 1v1? No. Moltres and Zapdos don't like taking repeated attacks and knock off scares them, but molt can roar gliscor out while being paired with something like Tusk, and Zapdos threatens Gliscor a lot with Hurricane. Part of the way you deal with gliscor is via teaming up on it, no mon can really 1v1 it, but multiple pokemon together can beat it enough in order to stop it. Latios can't switch directly into it, but something like washtom can and pivot out so latios can tera steel safely.
I don't think that gliscor punishes lazy building- I actually think its restricting on the builder. Of course no team should insta-lose to gliscor- that's just bad building. But the point is that it is really difficult to build a strong balance to bulkier team that can deal with an SD gliscor team consistently. It greatly hurts those archetypes' viabilities because its so restricting. It's not that those teams can't ever beat gliscor, its that those types of teams struggle immensely
The issue with balance teams is that other pokemon such as Waterpon and Kyurem, which do actually have much more limited checks (especially waterpon) constrain teams way too much. Balance teams should have multiple answers I believe. The balance team I have rn has heatran+geezing+mola+ting+lokix+iron crown. I didn't specifically prepare for gliscor, but it does well into it regardless. Heatran can pressure gliscor at around mid range health with tera+trapping, geezing can stop poison heal and tera on it, mola can sponge its hits well, ting can phaze it out, lokix does lots of damage with leech life, iron crown threatens good damage with tachyon cutter. These sorta teams again, should have multiple ways to deal with gliscor.