I'm not sure why post count matters here, I suspect one can fly millions of miles without ever encountering this particular problem, and one could certainly post on FT thousands of times without ever flying; the DL Contract of Carriage states this (emphasis added):
Originally Posted by DL CoC
FREE BAGGAGE ALLOWANCE-Subject to the provisions of subparagraphs (F)(2), (F)(4), and (F)(5) of this rule, the free baggage allowance and excess baggage charges will be:
1) Free Baggage Allowance for Passengers Other Than Children
a) Checked Baggage-two pieces of baggage of which the sum of the greatest outside linear dimensions of each bag does not exceed 62 inches (l58 cms.), and provided the weight of each bag does not exceed 50 lbs. (23 kgs.)
EXCEPTION 1: For codeshare services, each customer will be entitled to the free baggage allowance and charged the excess baggage charges (when applicable) of the Marketing Carrier, regardless of who the Operating Carrier is. Additionally, if the need arises for operational or safety related reasons, the Operating Carrier may find it necessary to "gate check" carry-on baggage. This must be at no additional expense to the passenger (i.e. no excess baggage charges).