Also is there any goddamn way to travel around the plains apart from hopping and skipping like an idiot for 10 minutes straight?
It's not very complicated to get some +Sprint Speed mods, added to a Warframe that already has its base speed set over 1.00, and some have passives and ability effects getting them further into SANIC mode, but Aarne described the go-to and most reliable way. And you're not only gonna use it on the Plains. You can also get a way to spawn the Archwing in the Plains, but it's kind of rare to see it from people as it's a bit wasteful to make and use for what it's worth. And it needs to have an archwing to actually spawn and a ship upgrade, so yeah, it's pretty redundant.
Also, you shouldn't really feel bad by getting randos to carry you in pubs. Team coordination isn't very neccesary in
MOST missions, and one overpowered super shinobi master could do it all on their own and have the rest of the squad just follow them pitifully trying to score some kills to seem like they helped, but it's hardly an annoyance for those higher level players. As for how it's avoided that absolute nooblords get assigned to missions way out of their depth, well, they'll rarely actually be able to get to those missions if they haven'y unlocked modes, options, and starchart nodes. But, those higher level players will be able to go anywhere they want, so even if they're the only ones with over 50 IQ in the squad, it'll hardly be a problem for them anyway. Really, the worst that can happen is that those nooblets feel somewhat "cheated" out of the experience, or just generally annoyed, which if you ever feel like that you can just switch into Solo real easy, and in most modes you're not really gonna be that much worse off. For them, the worst would be that you just don't fucking stop getting knocked down/killed, and it depends on their patience when will they just give up and go on their business
That said, you can join any squad that you're invited to and go to any mission that is picked, and the only way that low level players get walled off this are the few missions that need all the squad carrying a certain item (archwing, keys, invasion items, yadda yadda).