If a new viewer tuned in to DS9 S6 they'd be utterly lost.
Not just that. If you tune in an episode of TNG and didn't like it, well okay, because at the end of that particular episode it was over.
If you watch a episode of DS9 and didn't like it, you're screwed, because the theme of that episode is going to continue for the next few seasons.
The Enterprise Dee is in a battle, and you don't really care for warfare/combat episodes, the next episode of TNG will be something different.
If you didn't like the Dominion War, isn't that just too bad? 'Cause that all you be getting for a while.
Very true. Personally I think Trek is more fun when it's a new adventure every episode, with the occasional two parter and references to earlier episodes. DS9 was okay, but TOS and TNG were my favorites, and that was partially because they were more fun and less caught up in try-hard political seriousness that lasted for seasons at a time. That's not what I ever really wanted out of star trek.
Don't get me wrong, though. I think DS9 was a pretty good Star Trek show. Certainly better than any incarnation that came after it. It just never grabbed me fully and part of that was because I didn't care for the ongoing struggle of the "look how spiritual we are" bajorans or the battle against the cheesy dominion. It had plenty of great stuff going for it though, like a very interesting supporting cast and some classic episodes.