They may have issues with, you know, E3 and the ESA organising it, not the idea of having a rough period when people expect big announcements.
E3 is not some abstract concept of having a big game show in June. It was a specific event, that started as a trade show for the industry and investors and became entertainment/advertisement when the organizers realized there was a lot more money to be made that way.
Until publishers just all realized they didn’t need it to be heard anymore, and doing their thing was a lot easier and less expensive. Making your own conference is quitting E3.