Well, as a relatively new vaper (started around late January), I think I've advanced pretty quickly. I'm making my own juices, go RTA/RDA (haven't really touched the clearo in a few weeks (or half my vaping life), and am waiting for my first mech mod (SS+brass M16!). Still, when I started, I wasn't sure whether or not I'd be into the whole vape thing, let alone the whole rebuild your own X thing, so at the time, the less commitment meant the better (even if only psychologically so). While I was pretty confident about RBAs, I did want the assurance of something I knew that was easy (ie load coil head, fill, done) vs perceputally time-intensive (ie RBAs, though that turned out not to be the case). The same for juice. The DIY juice thing pretty much came from necessity (shipping juices w/ nic is ...pricey and relatively time-intensive here; plus, the juices I got initially were promising, but ultimately unvapable (as they were)).
Given shipping time and fees, and local costs, if I had to go the mech mod/DIY juice/RBA route off the batt on something I wasn't sure I'd like (which also means I'd have to get a mod, batteries, a charger, PG/VG, nic, etc etc, determine what my "vaping style" (or parameters for enjoyment) were, and learn/re-learn several disparate subjects at once- easily over the cost of DIY, even if only in the short term), I probably would've just stuck to rolling tobacco and cigaettes, while vaping on occasion (at best). Plus, where I'm at, vaping venues are in short supply and vapers even shorter.
All to say, even though I grew out of regulated (well, not completely- I still like and am planning on using my MVP 20W) mods, clearos, and pre-made juices relatively quickly, there still was a point to it and if I had to do it again (without knowing what I know), I'd still do the same. If my descent into vaping madness were a chemical reaction, my starters were the intermediary- Unstable and easily discarded, but wholly necessary to lower the activation energy.