These bodies are used, only very rarely, by wildlife shooters, and the ones that do do typically only use them with the very longest lenses, like the 600mm f/4... which is already out in RF mount and which most of those users already own in EF. The question that was asked is why would Canon release this body without big pro sports+ lenses at the same time, and the answer remains the same: the people who buy this body don't rush to buy a whole lot of lenses and the few lenses that they do regularly use already exist and are not due for an update. That you step outside what Canon have said is the primary market and also included wildlife shooters does not change that.
Also, if you check out the wildlife pros who play with cameras at this sort of budget, you'd know that even with 600mm + 2x TC available, most are still opting for the additional 'reach' of high-density sensors like the R5, 7D2 and 5DS R—24mp 35mm is categorically not made for them—while most 1D X wildlife shooters who were not yet convinced by the existing R bodies are also not the market that will be swayed by this, since the major hurdles stopping them from switching mostly come down to the continuous battery life in the field and the lack of an optical viewfinder, which obviously are not problems the R3 sufficiently solves to beat the 1D X in those areas. (And it'll be a fair few generations before any mirrorless camera can, if ever.)