...to you. Agree with most of your points, but to answer your question:
"Why would a person switch their entire system - not just body, lenses and flashes and everything else - just to avoid Canon mirrorless?"
The answer might be:
- Someone has been shooting with an SLR since forever and does not want to give up that experience
- They hate EVFs altogther or never could get over the 'weirdness' first stages of trying one out
- They value something very highly that only an OVF can do -- responsiveness, use as a power-free spotting scope for wildlife, etc.
- They are luddites who trust principally mechanical devices more than overly electronic ones
- Perhaps they don't trust/like/want to deal with adaptors for their EF glass
- This may not be mirrorless related at all -- perhaps they have huge hands and don't want to downgrade their grip, ergonomics, handling, etc. with the R platform's more compact setup.
- A