These big companies spend tens of millions on homegrown tooling, even their own languages and databases, but they can't assign one dev to write a domain-monitoring tool?
This is a better situation to be in than some internal tooling that failed to notify someone because it got forgotten after the developer left.
If one dev had written it, how many times would that tool have failed by now? When the original dev left the company a decade ago, the tool has been transferred between teams six times, it failed a migration and the email address it used to send errors to no longer exists so nobody noticed, and it's literally gotten lost in the shuffle?