I don't know what advantage the Binding does vs Attaching, but binding results to me in a big mess.  I dislike it.
I tried it out, and it completely eliminated all physics on EVERY groom.  For some reason in my project I have no more Physics tab per Groom in the Groom window.
I have to try an earlier save.
:angry:

I had to add it back in using the "Window" in the hair asset viewer.
:angry:
:angry:

that is strange , works very well here on UE4.26.
You need bindings for mustache or body fur , have a look at your Project settings "Tick Animation on Skeleton Mesh Init" has to be unticked.

THX.  Binding is for Morph-sensitive stuff on the face, and then a head piece could be just attached I guess, right?
You now what else, I had hairs not root-attached to the skull I was using, so in UE4, these "side" hairs fly all over the place.  You have to make sure you root them to the noggin otherwise they go crazy.
And you know how much I HATE when my 3d apps go crazy...it makes me go CRAZY!!!!!

Take a look :  here I am using binding :   

https://youtu.be/Hf8SApIdQww?t=60

UE4,26 - Binding - Test

Bassline303 - I LOVE PSYCHEDELIC BIG FOOT!

Here's a YouTube video demonstrating the "Hair For Days" Groom Hair set from UE Marketplace. He demonstrates how to attach the groom to head and how to bind the groom to skeletal mesh. The YouTube demo has trouble binding the hair (hair groom splits in two). I thought this might be of interest here.

https://youtu.be/EXPb2AwgRf4

Hi Bassline,
Very cool:):)

Hi Joe Gideon
Thanks for the info, but the video is so small
that I hardly recognize anything
he does in the groom settings at all.
Greetings rosuckmedia

haha thx ,,, it was only a speed test but "PSYCHEDELIC BIG FOOT" could be a cool name for my next project :D

Yepp , tested it and does not work with "Binding" , It works with Head Bone.
Don' t know if it is a binding problem or a Groom Scale problem ... had this problem when scaling up or down the groom while importing , to fix it you will need the .abc file for reimport.