What benefit is there in taking more responsibilities at the workplace?

I was told a while back that this is a good thing but they never expanded on why it's a good thing. From my perspective, I fall behind on my other work. I do not trust my department coworkers to get the job done. I am currently taking on the responsibilities of a manager even though I am not. I was also being given even more responsibilities in the past that caused me to fall behind my work. It felt like a rat race trying to juggle multiple tasks while trying to finish them fast enough to do mine. Suffice to say, I had a meltdown that almost cost me my job. My managers have backed off and let me pretty much have full run of my department. I guess they are afraid that I will leave. I was kind of hoping they would fire me instead but they don't want to do that either.

This has however left me wondering what I am missing out on. None of the extra responsibilities were going to lead me to a raise, more vacation time, or a promotion, so what exactly was I going to get out of it? Just keeping my bosses happy?