It has always amused me when developers try to make their application's database layer vendor-agnostic. Not only does that restrict you to the most vanilla dialect of SQL imaginable, it's also a pointless exercise generally because it is orders of magnitude more likely that your app will be replaced and the database kept than the other way round.
It was much more important when software products were sold to companies that ran their own databases. You didn’t have the luxury of choosing which database your app would run on so half the job of a software dev was making running it on many different db so you didn’t lose the sale. It’s one of the many reasons saas became the dominant way to sell software.
Once you control the deployment environment it largely makes very little sense to spend much time on db agnosticism. But that’s also true of many other things that have left vestigial forms in our software today such as IOC containers, pluggable log libraries, configuration files instead of configuration code, etc.
