Good thinking. "Crossover Nexus" and "Monster Party" were near the end of S2, almost instantly followed by the Sonic episode at the very start of S3. Probably doesn't help that these crossovers were some of the show's biggest moments of online buzz and trending streaks.
I love me a good crossover, but many cartoon [and capeshit] fans get a little TOO excited over these things; the first question they'll ask when a new show from a well-known creator premieres is if it "takes place in the same universe as [creator]'s previous work." You got this with Disenchantment and Tuca & Bertie, and the creators of Phineas and Ferb even indulged in this trivial fandom obsession with their short-lived sophomore show. And I'm sure the creators of Amphibia and The Owl House are CONSTANTLY bombarded with pleas for a crossover between the two shows instead of just letting it happen should Braly and Terrace actually WANT to go through with it rather than stick with harmless little easter eggs. It's sick.