“The first 2.4 release was made in early 2012 (per Wikipedia), and despite being that old, 2.4 remains the current version of the Apache web server”
Apache 2.4 shipped in 2012 and is on 2.4.57 in 2023. WebSocket support arrived in 2.4.6 and HTTP/2 in 2.4.17, all without a major version bump. The 2.6 branch in development is underwhelming. Eleven years of point releases is what stable software looks like when nobody needs a new number to raise a funding round.