I think the "I Love Lucy" chocolate factory scene is perhaps a good analogy:
The chocolates start to come in too fast, and they can't keep up, but because they aren't telling the kitchen to slow down, they keep piling up until it collapses into a mess.
Except with networks, many of the senders keep sending packets until the receiver says that they've missed one (or three, or whatever it is), and then the sender slows down again. But if you're hoarding packets, that signal to slow down is delayed. And then that creates bufferbloat.
I also like to think of buffers as time. The buffer in front of a link is basically a bucket of time the size of the buffer divided by the speed of the link. 1MB of buffer, in front of a 10Mbps link, is 800ms: (1,000,000 MB) * (8 bits/byte) / 10,000,000 bits /sec => 0.8 seconds.
And so the sender is going to keep sending faster and faster until they go over 10Mbps, and start to fill that buffer, and then when they do fill it, they have to resend the missing packets, AND cut their sending rate.
If the buffer is large enough (and therefore the delay long enough), the sender "overshoots" by so far that they have to just sit and deal with all the "hey, I missed packets after X" messages from the receiver, until everything's caught up, and they they can start going faster again (we call this congestion collapse, because the sender can't send anything new at all, and once they've sorted out the state of things with the receiver, they can start again (slowly)).
Congestion collapse is the candy factory from the above clip: That mess that needs to be cleaned up before things can start over again (slowly).