Like with most things the wanna be's are actually the ones gatekeeping what the "real athletes" use.
In my experience most high level people I meet in whatever hobby/industry dont give a **** what you use. They use what works for them and just appreciate that other people are getting out there doing things.
The wanna be's are the ones who do a bunch a research and then are like "you aren't a real (insert whatever)"
Nonsense. They care because it matters.
I'm not a professional athlete, but I'm a high-level amateur cyclist. I'd probably place myself in the top 90th percentile in amateur cycling based on my Garmin, race and segment results.
There isn't a squiggly chance anyone in my field would use an Apple Watch for cycling. Plus, while all power meters, sensors and the like are generally dual-channel BT and ANT+, the constant is always ANT+.
Why? Bluetooth standards were not constant, whereas ANT+ was. It also suits pro athletes because you can connect multiple devices to one sensor (up to four), at one time.
With the advent of BLE, things have definitely improved for BT but it's still very hit and miss. I train indoors using my smart trainer and BLE frequently drops leaving me stranded in a workout (usually when I'm pushing hard and the adrenaline is rushing), but worst still when you're in the middle of a virtual race. The BT signal goes, and that top 5 place is long gone.
As a result, I've switched to using an ANT+ adapter and since then, I've never had a drop.
Some would argue the opposite, but ANT+ is a very robust and solid standard which is why high-level sports people use it. Constant data (which you need), reliable and connects quickly (which you need), and no faffing about having to reconnect every time you get back to your bike or reconnect a sensor.
Also, I want to add my ANT+ HRM strap battery life lasted an insane 2 years wearing it almost daily. The newer BLE strap that I have and I use this for my virtual training, lasts about 6 months. I also don't think I've ever changed the battery for the cadence / speed sensor on my 10-year-old roadie which is now used almost daily on my smart trainer.
Even my current roadie has a speed sensor and after 2 years and over 18,000km, it's still perfectly fresh.
This is why it matters.