Going back to Percy, I don't want to labour the point, but just a few selections from his Preface might make it.

xxxviii 'many of these reliques of antiquity'.
...those of our ancient English Minstrels; and the artless productions of these old rhapsodists....Yet perhaps the palm will be frequently due to the old strolling Minstrels, who composed their rhymes to be sung to their harps'

He then goes on to describe his sources the vast majority from the 17th century. Were there still minstrels playing on their harps then. The masques organised by the nobility certainly revived them in a theatrical way, but all the books I've read seem to say the minstrels were already disappearing in the 16th century, and that they are something associated with the medieval period.