My favorite concrete example is "unusual" amino acids. Quite a few with remarkably useful properties have been demonstrated in the lab. For example, artificial proteins exhibiting strength on par with cement. But almost certainly no living organism could ever evolve them naturally because doing so would require reworking large portions of the abstract system that underpins DNA, RNA, and protein synthesis. Effectively they appear to lie firmly outside the solution space accessible from the local region that we find ourselves in.

I agree with your second point though that this system is massively more complex than necessary for the behavior demonstrated.