It looks very plausible that stretching before you exercise doesn’t do much for you. Multiple older surveys suggested this.
Annoyingly, the studies linked in the previous paragraph are 2 decades old, and somehow I can’t find a large, well controlled, trial.
Not necessarily. You can be flexible and still have tight muscles before working out or because of a previous day’s workout. Your tightness point might be more than a less flexible person is capable of, but it’s still a tight muscle.
For me, I have flexible glutes relative to my hamstrings (not hypermobility), and I pull my glutes on a regular basis.