Regedits are indeed a scam. If you look into what they are and what they do, you will find they cannot improve anything. On top of this, your system registry is very sensitive and you can cause serious problems to your PC, so is a pretty stupid thing to do. There are some very predatory websites out there that claim to sell regedits. Some of these will do nothing, others will literally install mods/hacks to trick you into thinking they do something. It is a giant placebo effect, and people are taking advantage of gullible children to make money.
In Minecraft versions of 1.7.10 and earlier, it did have an effect but this is automatically disabled in 1.8 onwards. This was due to Minecraft using Nagle's Algorithm which helped optimize TCP packets. This could be disabled by editing your registry but this algorithm no longer exists client or server-side so you can no longer gain any advantage this way.
Here is some further information about it:
https://www.munchymc.com/forums/t/regedit-and-how-it-works/3317