Seinfeld is one of the few shows that "earned" its spot.
It wasn't going to be picked up after the pilot aired, but one exec believed in it, so they got he equivalent of 3 1 hour "specials".
S1 did enough to get a low episode count S2 which again did well enough to get a full S3. (to S9)
S4 and "the contest" is the point at which it skyrocketed.
Imagine being any other network going up against NBC in the mid-90's. You were competing against Seinfeld+Friends+Fraiser+Mad about you on the same night :O
Oh I see. That's interesting.