[messe]

Really? It's just a few commands away, all of which are completely transparent and documented in the FAQ:

https://www.openbsd.org/faq/faq14.html#softraidFDE

Granted it could probably be added to the installer, but that's hardly "Utterly complicated to setup".

[mrweasel]

Arguably it's a little weird that it's under "softraid", when you don't know that it's a feature provided by the softraid layer. It's easy enough to figure out after a bit of searching, but it's not the first place I'd look either.