I hardly can imagine a company that had invested only in Go and will need fat Go gramework. Seriously.
>Because they wouldn't want to have to maintain a lot of different technologies/languages, unless it's really necessary?
Not a lot of, but a number - once again, pretty hard to imagine something serious going on here. And startups will hardly chose Go as their starting point for obvious reasons.
>Because a fat framework in Go is going to be lighter than a fat framework in python/ruby? (memory reqs, cpu, servers, etc)
Absolutely not necessary. You can build framework in C and had results that will make you sad compared to that of Python. But even if it is - most likely it will be more expensive and you will have to make a choice. But okay, let's say it has some point.
>Because Go is easier to reason with/maintain in large codebases?
How so? In comparison to Python, for example.
>I can't understand how someone would hold such strong opinions in such matters
Hey, I'm not saying people shouldn't write fat Go framework, or stop doing if they've started already. If stars are lit - it means there is someone who needs it. I just don't get why would you use something like Go for this.