Sure they can also be used for outsourcing the writing process and producing text that doesn't resemble your own voice, just as any tool can be used for multiple purposes. Tools aren't responsible for how particular humans choose to use them.
Your process is similar in spirit to mine, although mine is a bit more fluid. I don't think it's necessary to disqualify words and phrases based on provenance per se, but rather on whether they're genuinely the correct words for what I intend to say and how I intend to say it. That's basically the test I use; if I know that I've intentionally chosen every detail of the text, that I've maintained consistency with my own manner of writing and speaking, and that I've faithfully encoded my own bona fide thoughts, then as far as I'm concerned it's my writing and I see no need to qualify that based on whatever tools may or may not have been used.