Lets not carried away here. I am from Karachi and I KNOW this is not truth. I still have family living there and it never happened with them. No one ever came knocking on our doors asking to attend their processions! but still I will let other members who are LIVING in Karachi (not some self- proclaimed karachites 
) to come and CONFIRM or REJECT this claim.
ADDENDUM: They do come for donations from time to time, but saying that it’s compulsory on every house to have atleast 3 members to attend MQM’s procession is simply not truth.