I don't get what the fuss is    Just make your artboard bigger and scale everything up. Adobe Stock has a minimum of 15 MP.

I'm guessing they are implementing this so buyers can purchase a decent quality JPEG from the vector file, otherwise it will be too small.

Adobe has two options - zip file with eps (any size) + jpg of min 15MP or standalone eps with 15MP. Shutterstock wants to keep only one option - min. 4MP eps.

I am contributor and buyer as well and I can tell you that working with vectors bigger than 1500px is just annoying to put it nicely. I usually work with 100% or bigger magnification for precision and if I want to change anything - even change one point on a curve I soon run out of screen space, even on 4k screen.

File size matters mainly because loading complex shadows, blends, various overlay modes takes much, much longer with bigger eps files - for both contributors and buyers.

Also, who wants to download and store gigabytes of vectors -  extra money for internet connection and storage, again for everyone - contributors, buyers and even Shutterstock.

That's why it makes very little sense to implement this change.