Yes, you are right many people are showing interest towards the IEO, compared to ICO and STO. Once after completion of their IEO, the coin automatically started trading in the exchanges, whereas previously many ICO companies failed to list the coin in exchange after the crowd sales.
they did not fail but indeed those who did not register to the exchange project were very bad to follow. because to register with IEO in a large exchange also has strict conditions. not all projects will be able to fulfill it. sometimes teams that are not very competent must choose new exchanges that may have easier conditions.