I went the opposite route. I actually started with an integrated system. Some cheap Japanese junk by Hitachi back in the 80s. I then got into surround sound and my music playback was via a series of surround sound receivers. My first "serious" integrated system was a Peachtree Nova 150.
I moved to separates because I was unable to source an integrated that I could afford/live with, that featured bass management. I have perennially faced space constraints which dictated bookshelf speakers with understandably limited capacity for bass reproduction.
Although I eventually managed to upgrade my living space and now use Canton floor standers for my main system, I still use separates because I like the flexibility when upgradeitis strikes. In my bedroom system I use Kef LS50s driven by separates which allows me to channel the signal through a subwoofer with a highpass filter that reduces the load on the little Kefs.
I"m fully cognizant that there are other means of accomplishing this, but there is a limit to how "separate" I want to get! :-)