This was a pretty eye opening thing for me too, as someone who’s always seen himself as a pure improviser too. (tangent - there’s also no reason I couldn’t have worked this out for myself, just looking at my own improvised playing, had i put the thought into it, and there’s probably a whole LOT to unpack there).
No solo is ever really PURELY improvised. It’s never TOTALLY unpredictable from note to note. There’s always an assortment of “stock” phrase and lick building blocks that a player is using, part of both their genre’s vocabulary, and their own personal vocabulary. Even if there’s a lick where the player may not always play it exactly the same way twice, there’s the core framework of the lick, and muscle memory is definitely there. This is especially true of the faster stuff.
So, while looking at improvising as “if I want to be able to improvise freely, I need a picking technique that can effortlessly play anything” can certainly seem tempting, that’s only one possible answer, and it’s probably the unnecessarily hard one. The other answer is, “if my picking technique functions in this particular manner, then I should build a personal vocabulary of licks and runs that i can play quickly and can improvise around that work well for my picking technique.” One of the things I’ve learned here is that I pick with escaped downstrokes, so I’ve made a point of working more fast picked runs into my playing that flow naturally with single-escaped downstrokes, and now I tend to work things like variations of the Gilbert 6’s pattern into my playing, maybe linking the motif together in different ways and moving it around the neck, but using that basic framework a lot for faster picked runs, because 1) it sounds cool, and 2) I can do it pretty efficiently.
I think this concept taken to the Nth degree is Yngwie - he swears he improvises most of his solos, in the studio AND live, and he has an extremely regimented picking approach where he can reliably be depended on grouping runs in certain ways to align for his picking hand, or using economy picking in certain ways, or mixing in pulloffs in certain ways… but that doesn’t stop him at all from improvising.
Think of it maybe as like a creative limitation; sometimes imposing certain limits on a process for whatever arbitrary reasons can force creativity n other ways.