They only work in that capacity if you already watch a lot of memes, so they effectively act as a shibboleth (in-group out-group separator) for separating people who spend a lot of time on reddit from those that don't.
They still help a lot to keep the audience alerted as long as they are funny or surprising without meta information. Adding "Confused Nick Young" to underline, well, how confusing some features are, will still be understood perfectly well by those who see it the first time. On the other hand, memes like "Scumbag Steve" [2] are indeed problematic, because there is no way to understand the point the author wants to make without prior knowledge.
They aren't fun, don't have anything to do with technical content and just put me off, specially if the presenter thinks s/he could have a 2nd job as stand up comedian.
Most public presentations / speeches contain a few jokes. They don't have much to do with the technical content either, but they help people pay attention and ease in the speech.
It's not like we don't have enough boring powerpoint presentations already. It's also not like those going into the trouble of compiling the slides and sharing their knowledge owe us anything...
Well, others don't compartmentalize things so tightly.
Most would welcome one or more jokes in a developer speech. So much so, that it's common advice for any kind of public speaking and presentation to add a few jokes to lighten the mood (you can find thousands of articles, books, and public speaking training sessions advising about this).
Some of the best technical speakers add humor in their presentations (often lots of it, e.g. Raymond Hettinger).
I see how it can be annoying; for me it's only mildly entertaining. However from a structural point of view I have the feeling that it's it's fine if only slightly obscured (how I am, what I don't like about notebooks point 1, example, point 2,...). At least at the end there's some summary slides that states his main points/gripes (how you could win me over)
I assume it works much better in a live presentation, where he is talking while running the slides. A 10-20 page deck or 3 page paper would have communicated this more readily as a stand-alone.
Also they are lighthearted and fun and life is short so why not have some fun even when being serious?