Exactly! They also have that so it kind of makes you go [Insert Fax noises] and I genuinely don't know if there are exceptions for certain Ads.
Still, my experience was with Facebook, not Tumblr so I wouldn't know much on that department.
The thing that I can mention tho, (after checking 2 replies above) is that... Tumblr is actually a pretty active site but it mostly focus on fan content. Fanart, fanfiction or even takes on characters from series tend to be WAY more popular and have WAY more engagement than Original content.
Like, a Supernatural fanart that I did
Stuff regarding my comic, lol