Kinesio tape can be used by anyone, it's just strapping.
There isn't any solid proof that it works to support the muscles as the research is very sketchy at the moment.
If an athlete believes it will help them they have more confidence. A bit of a placebo effect.
Andy05, you are right that the research is not robust. But like many things without a lot of well-designed evidence, there is likely some benefit to it. Time will tell.
In the meantime, I agree with phili that an untrained person simply wrapping duct tape on a sore muscle is not a great idea.
All sorts of supports are available on the market, that do provide protection and support, however using them with an injury might help create a muscle imbalance and then cause further injury.
The tape is just a fashion item, unless there is some specific research that the tape helps do anything then it is just a fashion trend. Then Physiotherapists should need to take a course on how to apply the tape before they are capable of using it, I don't know of one in existence so they must just be using a best guess effort from experience.
It's just a fashion statement, use it all you like
I have been using kinesiology tape for a long time now and it really does help. You do not need to be licensed or certified to apply the tape. It does support while giving full range of motion so even if applied wrong, it won't cause any problems.