There was a time when quick detach came in different forms, and none of them ubiquitous. The popular QD sling attachments are QD swivels, HK hooks and Magpul's Paraclip. Uncle Mike's QD swivel may still be around for hunting rifles and Mini 14s, we don't see them on ARs anymore.
QD sling attachment has its uses but in our opinion, it's a solution that's not suited for every application. The ability to quickly get out of a slung rifle is very practical and should be standard on all duty and defensive rifles, but nearly everything has a cost. The QD swivel should be of high quality, and the QD socket and QD swivel adapter should be steel lined, or simply made out of steel. When either falls short, the liability a poor quality QD swivel and aluminum socket that wears quickly present a compromise that makes QD a point of failure.
A fixed swivel has a low profile, is mechanically simple (far fewer moving parts), and a reliable means to attach a sling on the handguard. For years we've been putting QD socket sdapters on our handguards and a QD swivel on every sling, we came to a realization it's wholly unnecessary (your experience may vary). We use our own CSF (Carbine Sling, FCD) that has an emergency quick release on the buttstock side of the sling. We still like a QD sling swivel for a buttstock attached sling for its ability to rotate.
We developed a fixed loop MLOK sling adapter with Rooftop Defense, and below is Sol's (owner of Rooftop Defense) exepreince.
A sling loop that mounts directly to a MLOK rail has been something I have wanted since 2016. As a shooter, I have found that QD swivels at the front of the gun like to meet Mr. Murphy and sometimes detach themselves at the most inopportune times. By removing the QD swivel and QD socket, we achieve a simpler setup that’s more robust and better retains the weapon.
In my personal use, I like to pair a fixed loop at the front of the gun, such as this one, with a QD sling swivel mounted on the buttstock. This allows me to reap the benefits of fixed sling retention on the gun’s forend, but still quickly remove the weapon from my person when wearing full kit or fully separate an AR upper and lower for maintenance purposes.
For Forward Controls Design's part, we've been developing simplified sling mounting solutions that do away with QD swivels. Quick detach isn't necessary in every application, it also adds additional hardware and complexity. Quick detach has its place and uses, for those that want the QD feature, we offer MSQ-H (MLOK QD sling adapter) and ESF-H (End plate with QD sockets).
Below is a QD swivel that lost its ball bearings. If you do like and use the QD utility, we suggest a steel QD swivel made in steel, and made in USA.
Below is a good illustration that shows the difference of a sling mounted to an MLOK handgaurd via a QD swivel and QD sling mount vs a sling mounted via MFH:
Individual experiences will vary. If you like your QD swivels and find them useful, by all means keep using them. QD isn't the best solution for everyone, neither is a simple fixed loop, choose what makes sense for your rifle.