This is entirely possible, though to me it seems more likely that an executive team ruled out doing transitions in batches. Then, when their online banking enrollment system encountered some reasonably-sized subset of Simple's 3 million customers Saturday morning, it simply keeled over.

In my account's case it was able to provision my account when I enrolled, but the web portal then threw up some opaque errors and didn't let me complete enrollment. Without the latter steps of 2FA/security questions/etc that I couldn't complete, my account was locked without access until I could reach a phone operator.

Ouch. Hope you didnt keep critical amount of money on that account