Earlier quoted context omitted.
1MB per photo is fine. It's the content after all. Many sites today will load 10MB of JS and custom font crap alone, just to show a few paragraphs of text. I don't think the point is the size itself, but it's the content vs. bloat ratio.
1MB per photo is massive. Its easy to compress photos down to 100KB or less.
1MB per photo is tiny when the photo is the content. You need ~100KB for a high quality 512x512 WebP. AVIF will be slightly better but still doesn’t have universal support.
We’ve had 4K (8MP) screens for a decade now and normal DSLRs shoot 25MP so you can zoom in.