It is only applied to the "last statement of a subroutine". Not to the last statement of a do block?

The line you read may only have been talking about the last statement of a subroutine, but it applies for the last statement do blocks and everywhere else a return value is needed from a loop. You've even demonstrated this yourself.

But suddenly, you read a bit of the documentation, apply it to the wrong circumstance, assume that your misinterpretation is the only interpretation.

Actually, you're the one who is being a slave to the documentation, not listening to anything else.

And I'm pretty damn confident that I could find numerous examples of you using, and recommending the use, of the return value from a block.

Straw man. It's the return value of loops that's not defined, not blocks. eval and do aren't loops.