My experience is that it's often not the developers at all that cause a program to get bloated, but constantly changing client/user expectations. Or in other words, a program is developed and it starts out simple. Then, one of the following happens:

1. The user/client comes across edge cases, and has a very specific thing they want done in that situation. Unfortunately, it's the complete opposite of what the system would usually do, so said case has to be specifically patched to act in a certain way despite making the codebase a confusing mess to figure out. So one tiny part of a certain web page gets different padding or line height because the client/user thought it looked better in that one situation, and no one thought to say it was a bad idea.

2. The project's spec was wrong and hence it was the wrong thing to be building in the first place, but no one liked the idea of starting from scratch. So you end up with a program that's meant to do one thing but has been crudely hacked into doing something completely different and hence half the features are utterly useless.

So it's not the developers fault in these cases, its management not knowing what the team is actually meant to be building or spending a lot of time trying to provide exceedingly random and useless 'nice to have' touches.