Thats indeed very a similar situation because i dont agree with those either. If something forces the entire tier to adapt itself and makes previous uu staples like umbreon and snorlax drop in both usage and viability it is metagame defining and thats what makes it one of the best pokemon in the tier. Youre absolutely insane if you think this is not an important factor.
Once again, just because it's the -best- (read: most ubiquitous) special wall in the tier doesn't determine viability. While there may be a weak correlation between Usage and Viability, there is by no means any evidence of causation. There are plenty of threats that are used far more than they should be, and plenty of criminally underused threats that are in fact extraordinarily viable. There are a great deal of factors besides Viability that determine usage; whether it can fit on all different types of teams (check), whether it has very little competition from similar pokes with the same role (check), whether it performs a role usable by all teams (check), and whether the hype surrounding the poke is more than or less than its objective worth (check).
Secondly, part of Florges' influence and usage on the metagame has to do with the fact that it's practically the only (bar Aroma) viable fairy in the entire tier. When you have that kind of corner on the market, of course the usage is going to be incredibly high, of course the metagame is going to "adapt" to you - it's not adapting to the introduction of the pokemon, it's adapting itself to the introduction of the type, which manifests itself in Florges, as it's the only really good fairy. In other words, if Darmanitan, Entei, and Arcanine were all taken out of the picture and banned to BL for whatever reason, and Victini became the only strong physical fire wallbreaker, it wouldn't increase its viability. It would increase its usability and its commonness, as teams who would have put one of the other threats in its place move on to using Victini, as it's the only available option. It's not like the UU metagame, or any metagame, is constructed proportionally by the amount of offensive and defensive threats in the tier, it's constructed based on their relative effectiveness.