Hello Jose
I see your point. ABAP Repository controls the version and merges if two developers are working on same file, but it's not as powerful as GIT when it comes to development on UI5/Fiori.
But there may be a way to configure an external GIT in SAP Web IDE to achieve a better source control. Please take a look at the following guide where it explains how to connect to a GIT from the SAP Web IDE to see if it fits your needs:
SAP Web IDE Dev Guide (Local Installation)
Best Regards
Luis Becker