Many stations who object to using LotW is because of
the hassle in setting it up. It did take a week for me waiting for the postcard, minor but an annoyance. DX stations may have more difficulty although most do have the needed online access to email copies of documents.
It does seem more complex than needed but that horse has been beat many times. Short of a total redesign, we have a system that is old and slow, but prevents some faking of contacts.
All I know is that I have countries that confirmed on QRZ but aren't dealing with LotW so DXCC is just a bit harder to get (Nicaragua, anyone).

Rusty, WA8ZID