The difference between "collection of packages" and "framework" is that "collection of packages" implies interoperable via API conventions, but otherwise standalone packages, which could easily be used in isolation alongside base R.
Whereas "framework" generally means tightly coupled components, in a "do things my way or the highway" fashion.
Technically speaking, it's not "impossible" to mix tidyverse with base R, but in general if you wanted to mix and match tidy vs base R syntax, you'd find yourself working "against" the tidy api rather than alongside it most of the time.
R is not my main language, but every time I come across a task and I need to make a decision between R vs tidyR, the two feel like completely different languages.
I also have some beef against some of the decisions/conventions used (e.g. abusing metaprogramming to pass variables and use the variable's label as a value, completely ignoring the variable's actual value, instead of passing it as a string or as an actual variable ... seriously confusing when you first come across it).