1. Attenuates the HF section to match the LF section
2. Augments the top octave to compensate for rolloff
3. Damps the peak at resonance

So to use a simple L-Pad will accomplish one of these things, but you'll still need to find solutions for the other two.

On some of my speaker designs, I use a midwoofer up to the point where it begins to rolloff. Most of these have some amount of series inductance, but it is used for response shaping rather than as a crossover. In that case, the Zobel is often omitted, and without it, the coil will not act as a first-order crossover. I call this arrangement a pseudo-first-order filter.