I think 'blame' is maybe too strong a word. I would maybe stride towards more of an 'explain'. and yeah, sometimes not having parented a child/ren people's understandings/perspectives of what that entails will necessarily be based on observation and dashes of ideals. but i suppose as the person receiving that information you do have to place it in context and then see if it warrants being offended/perplexed etc.

i have friends that dont have kids and sometimes they might say things that just dont apply, but then again, i meet parents in the schoolyard who parent so vastly different to myself that our conclusions regarding behaviour and management are on two completely diametrical paths despite us both being parents to wonderful, happy kids.

but as for your immediate thought bubble? I think it is valid. not to place judgement or invalidate that persons assessment but rather to put it into context and know if it relates to the situation or could potentially explain and give perspective to that persons statement. and then you can take it or leave it or even take on board some of it and discard the rest.