I’ve previously used versions 1.4.* and 1.5.* quite a bit for print, because I’m a one-man marketing department in a tiny company.
Scribus was (is?) somewhat finicky and cumbersome to work with. It had certain quirks and workarounds you had to learn to deal with. It lacked many creative features you find in bigger suites. I didn’t feel like I worked quickly and efficiently in it. BUT I got my work done in it nevertheless, and I really appreciate that it exists for the people that simply can’t afford the alternatives.
Nowadays I use the Affinity suite, which includes Affinity Publisher, a competitor to InDesign. It’s quite affordable and not subscription-based.
Nebula has about 10.000 videos, from only select creators. Youtube has around 1 billion videos, and everyone can upload. Nebula is not actually a Youtube alternative unless you’re in one of two specific target audiences:
Already established educational content creator looking for alternative platform
Person watching educational video content and not much else
I don’t see Nebula opening up their site to everyone and letting anyone upload content any time soon, and for that reason I don’t see them as a Youtube competitor at all. They’ve found their niche with curated quality over quantity.
Fun fact: The difference between 10.000 and 1 billion is… around 1 billion.
EDIT: Oh, it actually depends on the publisher too, it seems. In the digital ones I’ve read, it was small caps, but in some others it’s apparently all caps.