It's such a common aspect of languages too that many people don't even realize when they're doing it in their native language!

People get lazy - especially natives who don't get confused because it's how most natives will talk. For example, every word ending in "ing" in your comment could drop the "g" sound when spoken. Plenty of English speakers do that when speakin' and not many people would think anythin' of it until a frustrated person learnin' English asks why nobody is pronouncin' the endin' "g". Droppin', changin', and blendin' sounds is why learning a language by listenin' to natives speakin' is so important instead of crammin' textbooks all day.

Some might consider this a regional thing/accent and I'd argue that it both is and isn't. To the extent I tried to illustrate it would likely get seen as an accent but the occasional droppin' of it is somethin' I've heard across so many different English accents that I'd argue it isn't only an accent thing.

In the US it's mostly associated with a Southern accent and in England it would be the English Midlands like Brummie or Mancunian.