> Why does it go without saying?
Mainly because their motivations for doing so (namely: tax avoidance) were spelled out by the companies and their accountants in a series of email leaks. That's the thread we're in right now.
Australia and Canada have DTAs with India too. Pretty stable countries by most people's reckoning, potentially moreso than Mauritius and both with solid legal systems. Yet we aren't seeing PwC recommend to Silicon Valley investment firms that they spin up Australian shell companies to facilitate Indian investment.
We could probably speculate as to why not, or we could look at what the companies and their accountants said in the aforementioned series of leaked emails.
It's tax avoidance. It's not illegal, but it's not simplification or stability.