Sub only is a weird rule set?
In some ways, yes, it is more artificial. That may sound odd that a sub only match, where the goal is the submission could be more weird than a points rule set. But bear with me. The points system was more or less designed around vale tudo (no rules) fighting. Points were based on positions that would put you in the maximum position to do damage to the other person via strikes and submissions, while keeping yourself safe.
For example this is why side control and north south as positions doesn't get points. The ability to throw strikes from there is much less than knee on stomach or the mount or the back. Many would argue that those positions should be worth points, but that's another debate.
So in points matches sure some people stall, as they do in every other rulset including sub only. In points matches people fight tooth and nail to defend sweeps, passes, back attacks, etc. This causes lots of openings for submissions, and it's very dynamic. The downside is that if someone gets a point differential, they may just hold tight and not risk as much.
But in sub only there is also some artificial stuff. There is no need to scramble after you get swept or passed since that doesn't score against you. If your back is being taken and you don't have to fight to defend the hooks, your neck is not as open so you are harder to choke. If you are getting passed and you don't turn in or away to stop the pass points then you are less vulnerable to chokes and armbars in transition. So many people when they feel they have lost something like a pass, back attack, or mount will just do the Home Alone and defend, biding their time to escape later. Because it's hard to defend someone that only wants to not be submitted.
Also there are certain submissions and transitions that work from inferior positions in sub only, and it's not uncommon to see people allow themselves to be mounted so they can attack heel hooks. This is unique to sub only matches. Also I could go another few paragraphs on how there is zero reason to ever work any wrestling or takedowns in sub only, and there is no reason to bother passing the guard or even sweeping. There are very dominant positions that can be attained in sub only when heel hooks are allowed that don't need you to do either thing.
Tl;Dr - Points matches and sub only matches are both awesome. They both have pros and cons. I wish there was less debate about which was "better". I think people should enjoy what they enjoy and train what they want to train.
The unrealistic part of EBI is getting a free back control and a free spider-web after somebody successfully managed to refrain from tapping during regulation time.
I am not opposed to this ruleset, I like different rule-sets as they bring different action to the game. But I can understand the frustration a competitor might have when nobody can take their back through their own means, yet they lose in overtime by sub or riding time. Take J.Miyao for instance. He has gotten his guard passed a couple of times lately, and back in the day only by Keenan. But as far as I can remember his career, NOBODY has taken his back. Come EBI, and he loses on riding time. Well... it's unrealistic.
I still like EBI format, but it should to be thought as the ultimate ruleset, it should be thought as a contribution to spice up some tournaments.
Yeah I forgot to add this. The most artificial thing about EBI is that you can start with an armbar or back control on someone that you may never have been able to get on them in regulation. Geo Martinez didn't get one second of offense on Eddie Cummings at EBI 10, was defending an inside heel hook and triangles/armbars for 8-9 of the 10 minute match, and was gifted with the armbar control because of the overtime rules.