"Equalizing" is typically thought of as more or less elaborative tone controls as an extra measure on top of preconfigured passive speakers, and being able to attenuate a usually limited range of frequency bands. The rub mostly centers on the "extra layer" that is introduced with an equalizer, certainly as a separate component and in the analogue domain, which then messes up with the purity of the signal.
Essentially though an "equalizer" is not defined by what it usually does, how and where it's implemented or is regarded as, but rather its mere function of being able to modify a signal. This can be done in different ways and more or less intricately (/successfully), and in that sense a passive crossover is an equalizer just like a DSP/digital crossover, electronic crossover, acoustics, speaker placement, etc.
As such equalizing doesn't have to be an extra layer, but instead one that can be accessed at the very core of what is already the central "equalizing" device of the speakers; a DSP acting as a digital crossover - that is, replacing a passive ditto between the amp(s) and drivers entirely (lest not forget: the passive XO being a layer in itself that is here eradicated) - can be an extremely elaborative signal modification measure through a range of parameters that isn't only about attenuating a few, fixed frequency bands.
Indeed: why fix with limited aids as an extra, detrimental component addition when you can do it at the heart of the design with what's already there, from the listening position on the fly, and with a much broader range of parameters to boot?
