Even if/when comments like that aren't spam - which surely is sometimes the case - it's really not adding much anything of value to the dialogue.

Maybe it's just my personal opinion, but why comment anything at all if it doesn't say something more than such a generic acknowledgement. Why is it a nice writeup? What about it do they like? What did they takeaway from it? Etc...

Perspectives like those might add something worthwhile to a dialogue and enrich the flow within the community...