I haven't custom compiled a kernel in ages - does anyone still do this?

It used to be sorta-kinda-necessary back when memory sizes were measured in MB instead of GB. Kernels had to be under a certain size, the module system was a bit slow, memory was at a premium, hardware support was very spotty, etc. I remember applying some guy's patches to a 2.2 kernel to get full-duplex sound on the crappy sound card my Pentium 120 had (Linux has always had garbage audio support).

I think the last time I purposefully created a custom kernel was to enable some experimental scheduler code I hoped would give a performance boost. Was many years ago though.

These days you only do it if you want to learn the process or performance test a system. Or if you're running something like Gentoo - but even then you likely just use the 'default' configuration provided by Gentoo.