  Tidal disruption events (TDEs), in which a star is destroyed by the
gravitational field of a supermassive black hole (SMBH), are being observed at
a high rate owing to the advanced state of survey science. One of the
properties of TDEs that is measured with increasing statistical reliability is
the TDE luminosity function, $d\dot{N}_{\rm TDE}/dL$, which is the TDE rate per
luminosity (i.e., how many TDEs are within a given luminosity range). Here we
show that if the luminous emission from a TDE is directly coupled to the rate
of return of tidally destroyed debris to the SMBH, then the TDE luminosity
function is in good agreement with observations and scales as $\propto
L^{-2.5}$ for high luminosities, provided that the SMBH mass function
$dN_{\bullet}/dM_{\bullet}$ -- the number of SMBHs ($N_{\bullet}$) per SMBH
mass ($M_{\bullet}$) -- is approximately flat in the mass range over which we
observe TDEs. We also show that there is a cutoff in the luminosity function at
low luminosities that is a result of direct captures, and this cutoff has been
tentatively observed. If $dN_{\bullet}/dM_{\bullet}$ is flat, which is in
agreement with some observational campaigns, these results suggest that the
fallback rate feeds the accretion rate in TDEs. Contrarily, if
$dN_{\bullet}/d\log M_{\bullet}$ is flat, which has been found theoretically
and is suggested by other observational investigations, then the emission from
TDEs is likely powered by another mechanism. Future observations and more TDE
statistics, provided by the Rubin Observatory/LSST, will provide additional
evidence as to the reality of this tension.
