Would SQL Injection (other other problems) be solved by using Row-Level Security and Per-User Connection Strings?

Regarding the following OWASP Top-10 Vulnerabilities and database-backed web applications:

SQL Injection

Insecure Direct Object References

Can these not be solved by using a database that supports Row Level Security and by creating real user accounts in the database for each user and having them login to the database as themselves (via the web server)?

Any issues in this approach to be aware of (other than it killing connection pooling)?