Your take on the server usage of this idea is widely implemented. But the usual approach is not to allocate large block of memory and allocate from that, but to

Your take on the server usage of this idea is widely implemented. But the usual approach is not to allocate large block of memory and allocate from that, but to wrap malloc() with function that adds headers that track purpose of the allocated block and then free all still live blocks when the purpose ceases to exists. Both Apache and Samba uses generalized mechanisms for this (apr_pool and talloc, respectively), while PostgreSQL does the same thing in somewhat ad-hoc manner.