Wow, what did I start now?
I don't like playing without external p.a. either, and I've only done it maybe three or four times in my career (30+ years). My point was there ARE times it is appropriate. The job last week had me setting up on an interior balcony with cathedral ceiling. It overlooked the living/party area. The acoustics were such that the sound was very full and smooth. I put on a midi and went all through the house before the party started to be sure. After all it was background music. Midway through the party, as the sun went down and the temperature cooled off (this is Louisiana) the guests started migrating to the back patio/pool area. The hostess asked if it would be too much trouble to move out there.
I said "no trouble at all". She said to be sure and not bother the neighbors, so again I just used the keyboard. Outside it was even better. The dozen or so people were all very close and I could interact with them. At least four additional bookings resulted.
I had two complete pa systems in the van. One was the little Peavey Escort, the other powered JBL Eons in two different sizes. Believe me, if more was needed, I'd have used it. The party was reviewed by society editors from two different newspapers. When the reviews are printed, I'll pass them on, good or bad.

I did another such party recently when all they wanted was someone to play their accoustic piano. When I arrived it was out of tune badly. Not being a piano player in the first place, I asked if they minded if I brought in my keyboard instead. They didn't care "as long as it was no louder than the piano". By the end of the party I had passed out more than a dozen business cards to people who were amazed at the sound and performance. It was an 80th birthday party, but nobody had to turn up their hearing aids.

A few years ago I was working a few parties for Amtrak. It involved setting up in a double seat in a train car and playing while people ate and traveled. At the time I took a small amp because I had a Technics KN5000 that was no good for vocals. Today I would have just taken the PSR2000 and eliminated all the problems. There were maybe a dozen people all within 30 or 40 feet. It would have been perfect.

The other thousands of jobs I've played all required external amplification.

It's amazing to me that such issues can't be discussed without bringing personalities into it. I won't delete the string because most of the info here is interesting and useful.
DonM