IMHO, having employees (and otherwise affiliated) come to the thread can be a huge positive for the conversation, but it is indeed very important to disclose the affiliation! Don't fall into the trap of "well I'm just commenting my personal opinion, I don't need to disclose."

I think you can make a perfectly logical and reasonable argument about why it should be fine, but in the end it doesn't matter. It will backfire because it's been abused to the nth degree in the past and now people's antennae are up.

Transparency around affiliation is key. If you're commenting something of substance, then people will appreciate it and value your comment. If you're not adding anything substantive, then it's best not to comment at all.