nroff did do overstriking for underlining and bold. I don't remember if it did so for accents, but in any case it was for printer output and not plain text itse

nroff did do overstriking for underlining and bold. I don't remember if it did so for accents, but in any case it was for printer output and not plain text itself. APL did use overstriking extensively, and there were video terminals that knew how to compose overstruck APL characters.