Yes sadly people feel like a "need" to speedrun everything.
I usually check reactions on first pull (do a single group) and if the rest of the groups rushes by I know they expect a speedrun. Tho id never rush if people dont want to. Even in bray HM I ask "Slow or common speedrun?"
There are large threads about speedrunning in here because on one hand people complain they cant watch CS and co (not reading the texts in Tamtara HM ;_; ) and on the other hand you get bitched at for NOT speedrunning.
Especially in the 2 8 man story dungeons that is an issue. Even if both tanks healers and 3 dps are willing to wait there is that 1 dick that pulls and sorry not all healers are open to just let that idiot die and quit :/