I've never seen anyone do FBI in competitive play. It only happens here in casual play where people are literally coming in cold off the bench. For any competition situation, a real warmup and stretch should be done prior to the match starting. The 5 min warmup is literally just to lock everything in by running through all the strokes and meeting your opponent. It's not for 5 mins of ground strokes, then when a court monitor says start your match you ask for a few OH's and FBI. That's not how it works. lol
In every case where strict 5 min warmup protocol is strictly enforced there are always courts available for a real warmup. If people are so concerned with injury then maybe they shouldnt show up 1 min prior to the start of the match and then decide they want to regrip their rackets, apply sun screen and bengay to their entire body, before putting on their suit of armor which includes actual braces, neoprene braces, and very expensive tape that has no scientifically proven effect other than anecdotal testimonial evidence.
If it's a match where no warmup courts are available (like a public park that has only two courts or whatever), then there isnt really a court monitor to enforce the 5 min warmup anyway so everyone should be able through all the strokes, (ground/volley/OH/serve) in around 10 mins.
In social tennis people are showing up to general locations and general times, so they're literally being put on court after they arrive. When you have a match, you have a specific start time or large window where you can take a good warmup.