Disagree.

Most SO copy-paste must be integrated into your project -- maybe it expects different inputs, maybe it expects or works with different variables -- whatever, it must be partially modified to work with the existing code-base that you're working with.

Copilot does the integration tasks for you. When one might have had to read through the code from SO to understand it enough to integrate it, the person using Copilot need not even invest that much understanding.

Because of these workflow differences, it seems to me as if Copilot enables an even more low-quality workflow than offered by copy-pasting from SO and patching together multiple code-styles and paradigms while hoping for the best; Copilot does that without even the wisdom that an SO user might have that 'this is a bad idea.'

1 - I don't expect "not using a tool that generates bad code" to be the top option.

In some cases the benefits of doing so outweigh the costs (such as using a stack overflow answer that's stood the test of time for something you don't know how to do), but with Copilot you don't even get the benefit of upvotes, human intent, or crowdsourced peer review.

Copilot does not understand the code in toto and is therefore really useless for debugging (70% of all coding) and probably useless for anything other than very simple parts of an app.

I don't think that's important. Copilot, at least as it's been demo'd so far judging by the examples, is to help you write small, standalone functions. It shouldn't need to know about the rest of the application. Just as the functions that you write yourself shouldn't need to know about the rest of the application either.

If your functions need a broad understanding of the codebase as a whole how the heck do you write tests that don't fail the instant anything changes?

Since that's where the work of programming is, debugging connected applications (not writing fresh, unencumbered code, a rare luxury), a tool that offers no help for that is, well, not much help.