Many developers would prefer a single, universal browser. A single platform. A single input mechanism (a single development language, compiler, RDBMS, filesystem, cloud provider, backup system, etc). All for obvious, practical reasons, at least in the short term.
That would be devastating for the future, but if it makes projects easier today, many developers are entirely onboard.
That was very much a dominant position among developers in the IE days. Other browsers were a nuisance, and maybe they should just be cut out entirely.
If Safari weren't such an important part of the market, Firefox would have been cut out long ago and we'd be awash in "Made For Chrome (and skinned Chrome)" badges. It is only the economic necessity of supporting iOS users that keeps cross browser development alive.