...patronizing to the listener(s). They're effectively asking you--every phrase or so--whether a moron (or morons) such as yourself (or selves) is/are still following along with the topic, details, and such. Read the following text (a generic small-talk sample) with---and then without--- the ubiquitous rising vocal inflection:
"You know the other coffee shop. It always has that thing in the window. I heard it was part of a promotion they were running. Now there's one at the courthouse.
Without the 'UpTalk' it's, through a series of simple and specific statements, a reference to something one has noticed.With UpTalk anywhere or throughout, the listener is being at each instance *grilled* (with the implicit question-mark's subtext) as to whether they are still following the extremely simple (however noteworthy or not) topic or concept. I feel condescended to in the presence of UpTalk, and while I wouldn't advocate pimp-slapping its practitioners I wouldn't judge too harshly anyone who did so. Other than condescension, only self-doubt informs UpTalk; in the foregoing mini-monologe the speaker sounds unable to believe his eyes ("Now there's one at the courthouse." with rising inflection), and is asking for some confirmation from YOU of something they saw themselves....
Maybe some therapeutic smacks ARE in order; I've never gotten a positive response (or result) from mentioning someone's UpTalk to them as they use it, but sometimes mocking it as I speak back gets them to drop it (at least for the duration of our conversation), so who knows?

Fast Tip: If you want to slap, please try zealously mocking it back first. Then just lay the dialogue down where it is, turn, unclench your fists, and walk away.