I agree to disagree with you. Two people use the same equipment and get different results because of different factors in play. Assuming they are using the exact same juice, the varying factors would be a different technique used (one works better than the other's) or user error in some form or fashion. That can be the only explanation.
Most people who give up on cartotanks didn't have the knowledge of using a proven techique and following it to the letter, or were using poor equipment with a resulting poor performance and experience.
Sometimes it can be as simple as adjusting one's technique of their draw on a cartotank. Most often it is the result of not priming the carto correctly. I've guided scores of new cartotank users through their trials, and the vast majority end up enjoying their tanks.
I've been using cartotanks almost exclusively for 15 months. They give me fuller flavor of my juices, are more consistant and dependable than clearomizers, and are maintainance free. These work for ME.
Obsolete technology? I think not. I've done the RBA route. When they are working at their optimum, there's not a finer vape. But I find them to be inconsistant and fiddly, just as you found cartotanks. It's all about finding what works best for you. I don't appreciate people who dog a particular way of vaping because it didn't work for them. You can share information with others that it didn't work for you, but ridiculing people who get a great vape using something you don't like serves no positive purpose here.
RBAs tickle my engeneering fancy. But for convenience I use disposables. Back a couple of months ago I tried again. Got me some resurrectors and an AGR locking tank. REALLY, comparing a Vapeonly BCC, an iGo L and a carto tank side by side. First side by side the igo L (running a 1.6 double bow wick and coil) and the Vapeonly (with a broken in 1.8 ohm head, full wicks) at 8W on an SVD. Then, the carto tank. The carto DOES have a fuller vapor, thicker. That's the only pro I see to carto tanks.
Technique is something I research a lot. Predrilled cartos are usually too small, I used a saddle punch. Punched the first, primed it, if it was still dry punched the second one. Back then I used 70/30 PGVG (mostly Dekang).
On the other hand, the Vapeonly is foolproof. Open a new head, WASH IT (something nobody does), dry it with a piece of paper towel, fill it, prime the head by blowing INTO the clearo and boom! off you go. Best flavor comes from removing some whisps (and I mean it) of wick and soon you'll have plumes of vapor. MIND YOU not as saturated as those of a carto tank, but not bad at all. It's a small drawback for a lot of convenience.
Also I see people trying just one bottom coil and saying "I don't like it". Kanger is not the standart by any means, now other vendors are venturing into that too. CE3 XL regular and 3ml tanks will hold the dearest place in my heart. Never a dry hit, never burnt taste (except when I used the 3ml with the sleeve), but now are a thing of the past. As should carto tanks.
Oh, and REO users! Depending on the juice and the atty used the difference is negligible. I dug out my REO (stashed since 2012) and went into the comparison too.
Taste is subjective, so is convenience. I love slapping a BCC into the nearest PV near (sometimes my bedside PV, a V8 1200 mAh passthrough). The 33.3 chips don't rattle with BCC, only with cartomizers (try, you'll see for yourself).