So, you weren't locked either?

I'm starting to wonder how commonplace these locks really were, particularly for relatively low-level churners.

I object to your use of the word "abuse". That has a negative connotation, and I don't view playing by the rules as "abuse". It's optimization. If someone uses all the tax laws and loopholes available to them, to lower their tax liability as much as legally possible, are they "abusing" the system? Of course not. Every business does this; it would be criminal NOT to do this.