If you think you can replicate one of their core products by yourself or with a small team good luck.
Say AI enough times and your might even have a VC throw money at you.
Of course realistically your not beating SF, but your free to try.
Years I ago I worked with Oracle ERP which under the hood was just as you describe a fusion of different products from different companies that they had acquired. It was a maze of scripts converting from one format to another and thence to another, etc.