It's fairly common for commentary to be added to a reblog via tags rather than after the quoted post, so even reblogs without commentary may need saving.
No, the comment section on an average tumblr page:
X has shared this
Y has shared this
Z has shared this
....
Actual commentary? Not so much.
On a side note I tried going back there to see if the situation has improved and somehow the interface is even worse now. The blog I was trying to read would only appear as a slide in on the side and would disappear at the drop of a hat. I don't even understand how you are supposed to use it now.
Yes. The meme aligns with my own experience of tumblr, so I'm inclined to believe it over contrary anecdotes (of course a more rigorous study would be a different story)
