Yes, adding pepper is a recommendation not a mandatory step. But a lot of sites do, I.E. PagerDuty [1], paired with PBKDF2 as many apps requires to meet FIPS certification or enterprise support on many platforms.[2]

[1]: https://sudo.pagerduty.com/for_engineers/

[2]: https://www.owasp.org/index.php/Password_Storage_Cheat_Sheet