Over Pesach and Sukkos, it is common to find segregated minyanim in which those who wear tefilin sit in one section while those who do not sit in another, or completely separate services for both. Where does this practice originate, and why would segregation trump other seating concerns like makom kavuah?
Additionally, in discussing this issue with someone, he brought up an instance in which there were 9 people of one minhag who disbanded the minyan rather than count someone as the tenth since they were of the opposite minhag. This seems... problematic. For one, they seem to be deliberately precluding people from being in the tzibbur, potentially violating inyanim of poreish tzibbur and lo tisgodedu (this is less of a halacha and more of a drash...) Secondly they are potentially abandoning the opportunity for tefilah betzibbur for a minhag (to be clear, I'm referring to separation between practitioners and discounting those of different practice). Thirdly, they wouldn't discriminate in this way if the tenth was someone who just didn't have tefilin with him, so why is this different?
Why is the issue of tefilin on chol hamoed taken so seriously as to require segregation, discrimination, and apparent violation of other minhagim and halachos?