Wondering if this is a typical situation during these current times of UA...

My brother, his wife, and 3 kids had a late afternoon return itinerary TPA to DSM. First leg was TPA to IAH, then had an hour and fifteen layover for the IAH to DSM connection. Some storms (nothing severe, but some lightning) blew thru TPA at their departure time. They got an announcement while waiting on board at the gate that 'the luggage cannot be loaded due to lightning'. Ended up leaving about an hour and fifteen mins late....which ate up their entire layover in IAH. First flight made good time and landed at IAH JUST as the IAH DSM flight was kicking out of the gate and taxi-ing. So.....they missed their connection to DSM, and there were 13 total passengers that needed that connection. The big kicker...no more IAH to DSM UA flights the same day (as it was already early evening), and NONE the next day either (Sunday) SO they got re-booked on AA for a Sunday return, with LONG layover in DFW. And they were lucky....the other 8 passengers that needed to get to DSM had to wait an additional day to get home because there were literally no seats available to DSM for 2 days after the missed connection.

Here is my gripe (yes, I didn't even fly, but still...): why did that IAH to DSM connection NOT HOLD AT THE GATE for the incoming flight?? It would have been the last one of the day, and in fact the last one for the next two days. A 15 min hold would have been all it took, and the gates were almost right next to each other so all my brother's fam would have had to do is get off first, swing the corner, and get right back on the connection. Seems to me UA just cost themselves a bunch of money by needing to rebook 13 passengers on other airlines INSTEAD of simply holding for 15 mins at the IAH gate. Just seems so ridiculous to me. Esp when UA would have known they DID NOT have another IAH to DSM flight for 2 days after this one.