Barbara Pym was told in a 1963 rejection that books like hers, "despite their qualities, are getting increasingly difficult to sell." Sounds like typical rejection-speak to me, which has been going on for decades.
Notably, the rejection was for Pym's book An Unsuitable Attachment which was the first of her novels to be rejected by publishers after she'd become established as a published author. The book was considered too "old fashioned." It was published in 1982 after her death.