But i don't think that it depends on whether one can afford, for example, visual studio, or not. At least i can afford it (and that means that the majority of "others" can, too), but i will not waste money on that.
While i admit that the integrated development approach has it's value (especially for learners - the Pure-C IDE, back in the "old days" ;-) was quite helpful): i haven't seen in single one which doesn't limit you in some way. In almost every larger project you need to do something special which doesn't fit in the rules or hit some internal limits of the IDE.
With the toolbox approach you just exchange one tool which doesn't fit (obvious example: there a quite a number of make implementations and replacements). This doesn't really hurt. In the integrated world you have to bite the bullet: either use a workaround or replace it. The later is quite expensive since you may not only have to learn a new editor but may lose version control history or any other valuable feature of the old development environment. The former gets expensive over time.
In the business world the decision is easy: an integrated
suite costs
1000$, plus 1000$ per year of maintainance, plus say 3000$
training. That's it. (yeah, i know, that's not the full
truth).
The toolbox? 10 different programs? Can you calculate the
cost
and maintaince of that? And wait - part's of the
system may be exchanged? We need a policy against that
...
Management thinks different, and management decides. In the
open
source world there's a different kind of management, and
decisions are based on technical reasons or experience
instead of policy.
Not to mention platform independence, of course.