Also, Adam Ondra routinely climbs using this tie-in method for the reasons you mention.
> IMPORTANT: This knot is methodically NOT recommended and yes, it MAY untie while you are climbing. It can happen if your rope is new-ish (and that means it slides easily) and if you don’t tighten the knot with a lot of force. I am always splashing chalk on the knot in case of new rope to increase the friction and I do tighten it with a lot of force. The reasonable and recommended alternative, pretty common and very safe is double bowline. It is almost as big as eight, but at least it is always easy to untie.
https://adamondra.com/updates/my-climbing-more-about-feeling...