The pros and cons of ACV are many and complex. I haven`t found many neutral opinions, it seems to be quite a marmite thing.
Nobody is advocating taking lots of it, so the effect is of small amounts, but there are cultures that have done this for many hundreds of years, so for me this falls into the "it's probably a good thing because people have done it for a long time and continue to do so"
Why, is a different story - on the most basic level, you know how the taste of a potato becomes sweet on the tip of your tongue? so this is one of the biggest indicators that we can turn starch into sugar very effectively. ACV inhibits that somewhat, and this is the biggest reason for advocating it's use, particularly as a drink before a meal.
If you already do not eat starches, then of course that will have less direct effect.
Then - it's fermented, so all the benefits of eating fermented products apply - feed and nourish your gut biome etc.. but again, very small amounts, so little effect.
For me, I actually really like the taste - was something of a shock. I read Jesse Inchaupé, who recommends it as one of her food "hacks" - but immediately did not like it. However, switching to a "raw" ACV from Aspall - think scrumpie compared to cider - gave it a much more rounded flavour, and then adding to carbonated water (sodastream) - and bizarrely adding a touch of salt - turned it into something I now really like... and having given up drinking actual cider etc, I find this to be a real tonic ...