The t-distribution approaches the normal distribution with increasing degrees of freedom. It is certainly more relevant in for example hypothesis testing, since t-Tests (variance is estimated from the data) is much more common than z-tests (variance is treated as fixed and coming from a normal distribution).

In all of statistics or probability theory, the normal theory is however way more influential.

Nonetheless, it's a cool bit of history where modern statistics got its roots. As a lover of both statistics and guinness, i approve!🍻