Question: Why do Players Request Trades and Then Cancel in Less Than a Minute?

I've been noticing that a lot of players will run up with an inventory full of legendary items and request a trade with me. Since they're not offering on any of my items, and their inventory is full, I assume they're trying to sell me some of theirs.

Yet I've also noticed that they cancel the trade after like 45-60 seconds. Do people realize how LONG it takes so scroll through a lagging inventory at all of your legendary weapons/apparel / rare plans?

I'm posting this question in case I'm genuinely missing something here. Does this happen to other people? Do you do this to other people? What's the goal here? I've got plenty of caps but I need more than 60 seconds to actually see what you have...