You are correct. Keep in mind though that not all frames and weapons are worth holding on to. I've had a couple frames and numerous weapons that I've leveled up for mastery points and then sold because I wasn't going to use them again.Also, the game has a trading system. There are some mods that people will pay a lot of platinum for if they're maxed out. It takes lots of time and effort to max them out but if you put the effort in you can get plat without buying it.
Regarding the review, he didn't even mention Defense and Survival, which are the two most action-packed modes; there's no downtime in those. Also the crafting is just down to personal preference. He said the wait time building weapons killed his motivation to play; on the contrary, that's exactly what keeps me coming back, knowing I'll have a new weapon to try the next time I play.
The wait time on frames can be excessive, but after you build your first one it's not so bad. If you plan it right you can have a couple to play with while you're building the next.