But the point of FP is that it makes explicit that you've got that list of changes
No it doesn't.. at least not inescapably so. The list can be a series of evaluation contexts from nested function calls. That list of contexts isn't a first-order programming construct like a variable or a function ref, so you can't step back through it to see your previous values. Nor is the index 't' a first-order construct, since it's represented implicitly by the level of nesting. So what was hidden in an lvalue can remain hidden in FP, it just hides in the call stack rather than in a register.
the dynamic scoping straw man (nobody forces it, and neither Haskell nor Scheme nor many others even support it!)
No, but they do support closures and/or currying. Both of those create a chain of evaluation contexts that's basically a non-first-order list of previous values with a non-first-order implicit index. They offer all the benefits and disadvantages of regular lvalues and/or dynamic scoping, just wrapped in a different kind of syntactic sugar. And both of them shoot the analytic simplicty of lexical/static scoping right through the head, because once again you have values that can only be determined in the appropriate runtime context, rather than from direct inspection of the code.
It's precisely that kind of "we don't have that problem" tunnel vision that set me to ranting in the first place. I want people to be aware of the operational realities of programming instead of comparing checklists of syntactic sugar features without taking the time to think about what those features actually do.
The reason #4 confuses you is that you're too wrapped up in the superficial features of the immediate example to think about the fundamental issues of programming they represent, and then think about how those issues can pop up in whatever syntactic system you happen to use. That kind of superficiality is unfortunately common in some parts of FP culture, and it has the capacity to really piss me off if you expose me to it long enough.