One more time for those in the back:
v0.x > v1 Breaking changes
v1 > v2 > v3 a couple obscure breaking changes, but practically none
18 months pass
v3 > v4 New, composable design, basically a new project
v3 still maintained, 3.5 years no changes. v4 2 years, no changes.
v4 -> v5 was supposed to be 4.4, but an internal dependency '^' got us, so best choice was version bump to prevent problems.