I went to KISS last year. My view was all the great bands are dying off and the new ones are just not that great. I was sure KISS are going to play music live and not skim on the show and I was right, you could tell it was played live and they must have spent heaps just on the fireworks. While I wouldn't say KISS is a band I would listen to that often at all I was not disappointed at all in the concert and well worth going to once for the experience.
I am still playing in bands in clubs/pubs and as far as I know people like live music, we seem to have a reasonable following. The issue is lack of venues, with only three having live music and each one having many bands on their books we only play about twice a month.
I know Countdown was pre-recorded and the bands mimed their performance and I am sure the UK version "Top of the Pops" was as well. I feel that is acceptable due to only one song performed by each band would have made proper miking up hard to do and keep the show flowing in front of a live audience. But I agree I don't pre-recorded music for a concert.
I feel Billie Eilish feel her target audience wants to hear what they know while they see just her so feels what she is doing is right for her audience.
She obviously knows something I don't because she has made millions times what I have earnt out of music. Maybe it is that the music is not important and something else is. As a musician sometimes I am asked what a song is about, I have no idea as I don't listen to words just the music. Maybe that is my mistake.