Personally, I think it's quite deliberate. Canon did this with the EF mount. 50mm f1.0L....on the only body available at the time...a lowly EOS 650.Launching with $3,000 jaw-dropping lenses and a 6D2-equivalent body sort of seems to suggest this is what happened, especially if the follow-up bodies are lower-end products.
Only a gear head will buy a £2K body to get access to £3K lenses. Most buyers of the Eos R will buy cheapie EF lenses and use the bundled EF to R adapter. Gear Heads will want native R lenses...and will pay through the nose for them.
Canon will sell far more EOS R bodies than they will all of the collective R lenses currently available. They kind of win both ways...shift over priced R lenses to gear heads and shift buckets of Eos R bodies to everybody and anybody. Hell...even Sigma lenses work on it...