Your explanation seems very likely. My supermarket has different websites (for their card or online shopping), and one has a X-characters limit while the other

Your explanation seems very likely. My supermarket has different websites (for their card or online shopping), and one has a X-characters limit while the other does not. It has been a BIG hassle to get rid of all the problems I had (and still occassionnaly have some trouble). So while having a password character limit makes customers angry, it is better than breaking everything.