I dunno, old TV's won't work properly with Plex, and manny other legit apps. Even the BBC benefits from the 4k max firestick which makes it far snappier than iplayer built into our TV.Surely you don't need one then, Barrie?
We have a Samsung 65" smart TV from about 12 years ago on which the software is so bad, that were it in the MH, you'd definitely want a firestick.
Anything more modern probably does the same job, unless you're doing some 'extreme' mods to the firestick.
Equally our TV won't support the NowTV service we pay for, our Firestick does.