Working with any system comes with some inherent responsibility. Systems can be abused just as much as they’re used and it’s the abuse that tends to give a great system a terrible name. I think that happens with WordPress in certain ways.
While a simple caching implementation solves 95% of the major complaints people have with WordPress, I’ve lost count of the sites I’ve run maintenance on that have just way too many bloated, unnecessary plugins installed.
Please don’t take that to mean that my seeing a decent number of plugins activated correlates to a developer not knowing what they’re doing, of course that’s not the case.
That doesn’t change the fact that every plugin installation has an effect on your site. This article takes a deeper look at the effect than most. The testing process is interesting, and it’s neat to see the direct comparison of a few very well known plugins.