Yep. Frustrating. For some reason, you have to actually call to give payment and place the order. You'll most likely talk with Holly. She's a peach....and it's not her fault the system is so antiquated, so don't take it out on her.
No, has nothing to do with an upsell. I'd be guessing if I said I thought it's that they don't want the security issues of having a webstore where you can purchase things...or the added expense.
Another potential issue is you trying to order something that won't work with the upper or model you have. There are many iterations that don't plug and play...and the sales rep *should* know these.
For example....let's say you have a Type 1 lower and want a 6.5G conversion kit; it is only recommended/warrantied by RA in the Type 2 config.
Or....you want to put a 12" Type 3 mini gas system .308 bbl in a standard length XCR-M upper and bury the gas block. Well, you can't b/c the upper isn't machined deep enough for the mini gas system to be buried so you have to do a mini-length upper receiver and exposed gas block.
Those are the instances the sales rep are supposed to guide you through (as just a few of thousands of possible configurations/combinations).