But cygwin isn't linux, and on 99% of actual linux distributions you will never have to compile tmux from source. A better statement would be "And people wonder why Windows never became mainstream for developers."

Steps to install cygwin on actual linux? "(package manager) (install) tmux". And on OS X? Install brew by copy and pasting a command into terminal, then "brew install tmux". Even if you're an average consumer you could complete both of those steps without a problem. (Then again, why would the average consumer want tmux?) Windows/cygwin is the problem here, not linux.