Show me an official document/rule/whatever that states party size in DnD 5e is 4. Not for a specific campaign but as a general rule. Then we can talk about homebrewing.
Where's the one where it says 6?
The general average for a table is 4-6, but there is no correct amount. It can be played with just two players and a DM, or 9. The median rests around 5. (Edit: In practicality. I tend to prefer 4 max 5 personally around a table since it's enough for players to socially have enough people to play off of in roleplay, but few enough to give plenty of playtime for everyone to shine. If anything, I think larger party sizes are better in video games than in tabletop comparatively, for those reasons.)
To reiterate:
There is NO number that is 'the correct amount' for how many players are in a D&D campaign. Anyone claiming otherwise, is wise to ignore as they're being disingenuous at best, ignorant at worst.
However, there is a matter of preference. In a video game environment specifically, some people want a party of six, for any particular reason individual to them that is perfectly fair and valid. And not wrong. Just like a party of four is equally valid, both for tabletop and a video game. On the matter of feedback, that's basically it; A wish for the option to have six party members, even if it means resulting in the game being easier / not balanced for it. They simply prefer having a bigger party. It's a generous compromise, recognizing the workload a development process requires to do both (not to mention extra QA hours). That's being reasonable.
Instead the discussion should be about having the option for both in some shape or form, because as soon as people start to argue objectivity, they're almost always
objectively wrong. Because there is no fixed party size in D&D.
A simple google search of 'how many players in D&D' will give you a wide variety of discussions and results on the matter, and pretty much all sources agree that there is no particular fixed party size number.
