Sure, bind has a terrible security record, and that was part of the reason why people started writing more secure replacements like unbound.
NTP has a terrible security record, and that's part of the reason people started writing more small secure replacements like NTPsec and chrony.
Similarly sendmail's security issues resulted in improvements like postfix, which hasn't been swallowed into system yet, mostly kidding.
Linux often has multiple implementations for a given service and ease of use, performance, security and related allows them to compete. This is a sign of a healthy ecosystem and generally I think it's working well.
However systemd, by rolling this functionality into systemd subverts that system and the vast majority of systems will just accept the defaults. It also makes systemd huge and complex, last I looked there was somewhere around 5% of the lines of code in systemd than the entire linux kernel which I find scary.