See bug 124196 Comment #2. (I can't reopen.)
There's no such note in 188.8.131.52. Don't see what you mean.
The note is in the skype-184.108.40.206-r1 ebuild,
why are you using the old version??
I emerged the latest stable (220.127.116.11). I forgot to think about checking the later masked versions. Because bug 124196 suggested that the postinst note was ignored I created this one. Strictly speaking it is still a bug but even less important if it's already fixed in unstable versions.
You've misunderstood the issue, the postinst info is NOT inappropriate in 18.104.22.168 as it's not using alsa by default.