Continuality and familiarity are both huge aspects, especially for a position unit that relies on the guys next to you knowing what to do if x happens. The more these guys play together the better they know what each other tends to do.
You're seeing a worst case scenario this year. Lots of guys playing all over the line next to other guys they aren't as familiar with. A number of dudes who weren't even rostered to begin the year. Guys who are completely new to the scheme and what the call outs may even be. It extends to the TEs and RBs as well as they will have blocking assignments often. We saw it a lot the last few games, guys aren't familiar enough with each other to know who is going to slide on a stunt for example. It takes a lot of trust to say "hey, I'm going to stick with my guy because I know X next to me saw the same stunt I did and will slide to cover it."
I don't think it is a "complicated scheme" issue at all. This is what o-line play looks like when you are starting guys who weren't here to gel in the preseason let alone even on a roster a few weeks ago. The skill isn't there (or they wouldn't have been on the street), the familiarity isn't there (which is completely expected), and the execution is lacking because understanding scheme nuances takes time. This is one of the big reasons you don't see a ton of trades for offensive linemen at the trade deadline (almost none really unless a team is just really sour on a guy and wants to get anything back for them). Its one of the few positions where just being good at your job isn't enough, the unit really has to function as a group well.