Once, Anti-virus was king.
You scanned your files, maybe it found something and cleaned it up.
Then came things like 'Master's Paradise' and 'Back Orifice'.
Anti-virus companies said, 'this isn't a virus, we're not going to do anything about it'.
And so BOClean, 'The Cleaner' and TDS came to be. These were the original 'anti-trojan' programs which dealt with 'unwanted gifts'.
Eventually, the AV's were shamed into handling a couple of these. Over time, trojan authors decided that they could get PAID by taking their code and hijacking browsers.
Along came 'Ad-Aware' and similar and they were FREE.

As a result, those of us who handled TRUE nasties took the attitude of 'as long as SOMEBODY's taking care of that stuff, then we don't have to waste space on them, although we ALL handled the more egregious ones.
'Tracking cookies' and simple hijackers that weren't SPIES were left to the newcomers. In a sense, we did what the AV's did upon the advent of trojans, 'NOT our problem.' Eventually though, as the problem became more frequent, ALL of the 'anti-trojans' did 'spyware, adware, etc' just because it was an 'unwanted gift' as the 'scumware' as we called it decided to become just LIKE trojans and try to hide and SPY.

And still ... the AV's ... 'potentially unwanted software?' 'Adware?' Over the years as their commercial interests appealed, they created all sorts of new terms in order to sell an ADDITIONAL piece to what they were peddling. So 'cookie removers' became 'anti-spyware' and 'anti-this and anti-that'! So today, the 'hot term' is ...... 'anti-malware' because ... bad things are bad things.