A RegEx-based parsing system in JavaScript helps with the reference formatting. EndNote makes references uneditable (unless you also have a copy of EndNote) and often cannot adjust to a particular journal's idiosyncrasies...but I can do that easily with home-built software.
Zotero may be great, and I cannot really make an assessment one way or the other. All I know is that hardly anyone in my industry uses it. It's really a nonstarter. Often, people need special permission to get access to open-source software and IT departments do not look kindly on installation of these tools.
Not to mention, I can't think of one piece of software or database I was using in 2003 that I can still access and use except for plain text files. This kind of software has no longevity. For these reasons, the academic publishing industry has not really standardized the process.
After a copy of RefMan broke, following the EndNote acquisition, I remember a time when I had to reverse engineer the database so I could still access the contents. It was a big tabular file and there was a much easier way to make it work with a simple browser-based tool and a few lines of code. I made it work and showed it to my boss, who summarily rejected the solution, even though it worked much better than the original (broken) software and broken database files for hundreds of prior projects. He emphasized that he wanted a paid solution. I still don't understand the logic. These are the kinds of nightmares that I associate with any kind of proprietary software solution. Often, in publishing, we need something that will work now and will still be accessible in twenty years. That's hard to do with free software.