I agree with this, but if a person goes into it knowing that they need to start slow, a built rig could save a bunch of cost in the long run. A person has to be smart enough to know their limits.
Not at all trying to start an argument.
While I agree it is cheaper today to buy a built rig than to build one from stock, for a beginner this is the worst thing they can do. The core driving skills of rock crawling are almost always used by oneself on teh trail, or when helping others, skills such as:
knowing how to read the trail(picking out the right/easiest line for your/others rigs),
knowing where the corners of their rig are,
knowing where the wheels are and how to place them on the rocks when you can no longer see the rocks,
where their drive train components are and what type of rocks they will hit/clear rocks and how to place tires to prevent that,
getting comfortable being what in off camber situations with little chance of rolling,
proper use of throttle/brakes in acents and descents,
how to get yourself back on the line you need to be on when thrown off it due to rocks/tire slipping etc.,
how to stack rocks to get yourself/others through a rough section(components break, when they do is not the time to learning recovery skills),
learning to follow/give hand signals so you can be directed/direct others through a section/back onto the right line,etc.
These skills simply can't be learned with a built rig no matter how slow you take it. Starting off with a rig w/lockers/crawlers/38" tires will make the the beginner/intermediate trails no harder than driving the same truck to the mall, and as soon as a beginner gets to a section that does, he will be in way over his head. In situations like this, the results are usually rollover, breakage, or worse yet having to have someone else drive his rig for him(happens more than it should).
Another reason a newbie should start out with a stock rig, is so that they know how to fix their rig through servicing it at home, not standing on the trails side holding a part and wrench(if they even have them) and not a clue of how to use them.