My take is Dolby easily dominated the tape noise reduction domain being first and also Dolby tapes still playable on non Dolby decks, especially car stereos.
Dbx was superior performance but never really caught on as a dbx encoded tape not so playable on non dbx deck.
As for reel to reel, they were usually quiet enough without noise reduction, cassette not so much. And digital soon became more widely available soon after dbx 228 and dbx cassette decks hit the market.