If you can't coherently and succinctly communicate what you've done for clients in the past using visuals and words, then you aren't a very good designer. Presenting information and making it digestible is in the damn job description. While it might take some time to put together, portfolios are the great equalizer. They cut through all the credentialism bullshit (were your rich parents able to pay for RISD?) and social/race/gender bias.

I don't think I know a single person who would hire someone who is still expected to be executional without showing work samples. It doesn't have to be a bunch of novel-length case studies, just something. There's way too many "big team" designers floating around now who have gotten good at Fortune 500 company politics while never actually designing anything.

The exception is if you are management level, which at that point, it's more about what your team has done and not you specifically.