The way I conceived this idea is that with the sponsors listed next to the episodes, it would make it much easier to narrow down the EKAs (and more precisely, first appearances) for all the letter and number sketches, based on the Sesame Street Letter Segments and Sesame Street Number Segments pages.
If we decide not to keep this convention, then it would make it more frustrating to narrow down first appearances, in my honest opinion. It's more time-consuming to have to check each individual episode page to verify when a letter/number sketch first premiered than having the letter/number on the season page. Having the sponsors on the whole season page reduces that time-consumption.