Why do companies need to file form 8A?

I currently follow a company (DTST) in progress to be listed on the Nasdaq Capital Market (previously traded on the OTC).

After filling the S1 report with multiple amendments, they also recently filed an 8A form (or 8A-12b).
To learn about the IPO process, I tried to compare the SEC fillings of DTST to other companies recently listed on the Nasdaq Capital Market.

My question is:
I see other companies that got listed without filling the 8A or 8A-12B form, so why it is needed? I don’t grasp how it is useful.

*NOTE: I am not affiliated with the company mentioned, but I have invested in it.