Twenty years ago today we released X11R7, completing over a year of effort to split up the X Window System monolithic source tree into separate modules for each library, program, driver, etc. and to build it all with the GNU autotools instead of Imake. While we’ve recombined a few modules since (xorgproto instead of individual modules for each protocol definition) and are moving from the autotools to meson now, overall it wasvery successful and made it easier for us to maintain the packages we’ve kept going and to retire those we chose to let go.

https://lists.x.org/archives/xorg/2005-December/011616.html