This is certainly not the norm. I’m a GUE instructor and regularly dive non-GUE rebreathers (including a sidemount CCR
). Many in our local GUE community regularly dive non-GUE side mount and CCR. Our community photographer regularly shoots non-GUE teams while doing dives beyond her GUE certifications (but well within her experience and non-GUE training). None of this is an issue with any of the local GUE instructors. I am sorry you have had that experience in your area, but it is not the way it is everywhere, nor the way it is supposed to be.
Some things, like solo diving, deep air, and smoking will certainly get the community riled up a bit.
(On another note, 30/30 is a 30m gas, which would be a more logical reason why your instructor was questioning the dive to 40m)
I'm also sure it's not the way it is everywhere. But most of my diving is in The Netherlands were I live. I see it happen a lot of times, everybody here knows it's happening.
(I prefer 25/25 for that kind of dives. But that's not a gue standard mix, I don't like 30/30.)
To add a bit, I can think at least of one instructor evaluator (cave level) who regularly dives with non-GUE divers, and pictures are on Facebook - everybody knows it.
Also, when they made the side-mount and the CCR courses, where did they gain the experience? Someone in GUE was diving that stuff and building expertise, and that stuff was not within GUE standard at that time.
The point is not to dive outside GUE standards; it is to do it safely.
And diving outside our own training and experience.
In the past GUE was not offering so much training. (Fundamentals, tech1, tech 2, cave 1, cave 2 & rb80) Number of different training modules GUE is offering is nowadays around 30. Agency's are offering training for everything. I did GUE training because it was good training. I did learn a lot and did even pass the training. Should I take all the training that gue think which is required for my diving ? I don't think so, gue is just an agency and no police/government.
Even gue instructors are doing dives beyond their training. WIthout CCR2 you're not allowed to dive deeper then 51 meter with a ccr. I can give you a lot of examples were gue instructors are diving outside training and experience. I could say the same for sidemount. A lot of gue divers (even instructors) are doing sidemount dives without sidemount training.
I do think that sometimes things/standards doesn't make sense. In my example were I wasn't allowed to do a dive with a bottomstage and deco stage, I think it didn't make sense. I was diving with 2 stages during cave 2 training. Also when I finished cave 2 training I did a lot of dives with 2 stages.
When I passed my ccr1 my instructor told me I was not allowed to use my ccr in caves. Another gue ccr and tech instructor was telling me that when you did pass cave 2 and ccr1 you was allowed to use your ccr in caves. Different instructors are telling different things. Standards are not clear. There is no gue ccr cave instructor in Europe. A lot of divers even gue instructors are using their ccr in caves without ccr cave card. I already did a lot of cave dives with my ccr. Should I do ccr cave when there is a gue ccr cave instructor in Europe ? (Maybe the first gue ccr cave instructor in Europe is the same person who was telling me that ccr1 and cave 2 was enough for cavediving with a ccr.)
I do listen what gue instructors are telling me. But when I think I'm able to do a dive in a safe way and agree with the rest of the team I will do the dive. (I can still learn a lot and will do more training and diving. But time and money are limited for me. I can't spent 20.000 euro a year or even more for diving. I can't dive 5 days a week.)
I do think it's hypocritical to tell other gue divers what they can and cannot do when there are plenty of gue instructors who only follow the rules when it suits them. That's what happens regularly now. There are many people in the (local) gue community (here) who are annoyed by this. I don't think it does GUE any good.
This is one of the reasons my next training will be TDI/IANTD.