Nah. A flag is more than a "boo," much in the same way laws are (hopefully/sometimes) different from mob justice. It says: this is bad for x reason.

And a single yay is very little investment of time, but applause can be made to take time. If someone wants to spend a 20s clicking "yay," that says quite a bit more. If combined with "reactions" you get a bit more nuance.