1/ network calls are what I find still gets optimised by grouping API requests and bloating the exchange contract; but yes, if you're strictly clean coding, this will suffer too - it just happens less often than what the author of the youtube video objects to

2/ That's a fair challenge - and I definitely have more trouble reading through an absolutely ramped to the max collection of C# code (which reinforces the behaviour you describe) than a superscript; but for interchangeability, the middle between those two ends is typically better - you're trying to minimise functional context for the thing that a software developer needs to do. This has the additional failure mode that the feature that is envisioned (of sufficient complexity) never actually gets delivered, but the component parts that can be well encapsulated do. And this is because no one holds the full system in their heads. But this can be explained away to business as "there's too much complexity, we need another cycle" and "we need to iterate" and therefore the cycle continues.

I think I actually convinced myself away from encapsulation and separation of concerns in that last comment.