Indeed, it was a radical feature in 2015. The marketing name for SPARC ADI was "Silicon Secured Memory" and the marketing material from that era [1] says:

   Some programming languages such as C and C++ remain vulnerable to memory corruption caused by software
   errors. These kinds of memory reference bugs are extremely hard to find, and victims usually notice
   corrupted data only long after the corruption has taken place. Complicating matters, databases and
   applications can have tens of millions of lines of code and thousands of developers. Importantly, errors
   such as buffer overflows are a major source of security exploits that can put an organization at risk.

It's little sad that the SPARC arch is no more and even after 10 years, we still don't have this feature in mainstream CPUs.

[1]: https://www.oracle.com/technetwork/server-storage/sun-sparc-...