Webpack doesn't seem to have a shortage of contributions. What is your real concern?

1) A fragmentation of targets for complementary products. Any tool that must integrate with bundlers now has one more target.

2) A fragmentation of development efforts across competing projects. Webpack has many contributors, but they'd have 1 more if the author of Parcel built parallelism into Webpack instead of a new bundler.

Yes, you can. But you can’t force them if they don’t want it.

K. Who's forcing anyone?

Nobody’s forcing anyone but a lot of people including the parent comment complain when someone doesn’t want to work for free on the tool they use. Encourage people if you want, but don’t complain if they don’t listen.

By all means, do. People complain about things that make their lives worse, especially when it's avoidable, as it is in this case. There's nothing wrong with that.