Question about Canon EF 100-400mm f/4.5-5.6L IS II USM

The suitable lenses for the A7II are these E-mount lenses:
Sony FE 100-400mm F4.5-5.6 GM OSS
and this one
Sigma 100-400mm f/5.0-6.3 DG DN OS, Sony E

The Canon EF 100-400 doesn't make much sense because you would have to buy a relatively expensive adapter and the AF is not optimal. I had adapted this lens myself once with the Sigma MC-11 on the 6300 but at that time the Sony 100-400 was not yet available.
This is the adapter:
Sigma MC-11 Adapter Canon EF to Sony E

Yes, with an adapter, but it doesn't make sense. There are Sony and Sigma 100-400mm lenses that fit without an adapter. E Mount fits.