The drawbacks are many and the benefits are few.

Watching foreign films would be a pain, where is this in the world again, what does 19:00 mean for them? More exposition, or you just have to guess based on languag and accent.

I need this work done by our team in XYZ country, what are their working hours? (wow, look at that, still using timezones?)

When you arrive somewhere on holiday, now you have to get a sense of the time there. Or continually be thinking "what's that in my home time?/what's that in solar time", which is why solar time just makes more sense.

People aren't going to stop thinking in solar time, ever. We're hard-wired to be awake with the sun. It doesn't matter what the numbers are, you will associate them with the sun. The question then becomes, would we rather all use roughly the same numbers (timezones, what we currently have), or different numbers (everyone using UTC).

Using UTC solves only 1 problem, you can say verbally to someone across the world, let's make the meeting 15:00 - but this is already easily solved by using a calendar which converts for you...

There's a reason we have never used a single non-solar time, it's just worse and I think there's a reason these posts always end up on programmer focused places on the internet. Yes, I'm sure their job is annoying, and it would be easier to not have to solve time conversion problems, but the time conversion problems wouldn't even go away if you forced everyone to use UTC. You'd just start having to do conversions to solar time, or looking up waking hours (which is just timezones)

This is a solved problem.