That php-doc-standard also just "recommends" using a DocBlock. That would allow us to interpret it as Susi suggests. I agree over-simple doc-blocks don't help at all. Our PSR-standards also don't forbid us to skip docblocks? (We wanted to stick to established standards, even if they might be unpopular).
Imho if we make it optional we will still be able to point out during code-reviews for which cases we definitely would want a docblock. We also currently check if the docblock makes sense or needs to be more precise/extensive/... So that should work out.