Of all these various crackpot theories about the true authorship of Shakespeare's plays, there one thing I never got; a convincing reason as to why someone would want Shakespeare take credit for their work. It would have been possible to submit plays anonymously if they didn't want to be associated with the theatre or whatever.
I don't even think that much would be necessary. Several nobles wrote plays that were just meant to be read. Sir Fulke Greville, the Countess of Pembroke, and the Earl of Stirling are three I can instantly think of.