Sure, and I would normally agree with that, unless this is a common thing for that location (seeing it always busy, seeing frustrated people, etc).
Again, if you need to charge (and that could mean a saved trip at a supercharger or something) I would say go for it. But if you literally have a home L2 charger and never run out of range during your day and just want to because it saves you $1/week in electricity, maybe don't. (Unless the places are almost always empty)
I've actually run into more and more L2s being busy when I actually *need* it (well, I can swing by a supercharger, but the L2 would keep me from having to; no home charging option during that time). So I can kinda get people living somewhere that might not be able to charge and always seeing the L2 busy before they get there. Likely the Tesla guys have much easier time charging (more supercharger locations, more stalls, faster charging, etc) compared to finding an 3rd party site like EA or EVGo.
I tried to charge twice at an EA station near a grocery store and realized that out of 4 stalls only 50% were actually working and they're REALLY busy now that I know the empty two aren't working! It made me really glad I had superchargers to fall back on (which actually was packed when I went, but since it was a 16 stall location a spot opened within about two or three minutes).
So again, I can kind of understand others being a little frustrated or upset. Totally charge even if you don't need to if you notice the place is empty most the time when you drive by, but if it's purely about "Hey, it's free, I pay at home" maybe don't...