They're cheap, simple (don't require a complex BMS), predictable/safe, have a long-enough lifetime and are easy to recycle. The biggest drawback really is weight - and thereby shipping cost - but for long term stationary applications that doesn't matter.

Lithium Ion attached to a supercapacitor with a sophisticated BMS is a much more complex setup-- yet even so, it will probably end up being the gold standard in the long run at this point, I would say even in most places lead-acid is still being used. I would not have predicted anything like that even five years ago, but barring some unlikely breakthrough it seems like where we're headed.

Honestly it’s just market inefficiencies at this point. I build battery packs for drones and RC planes and the lead acid stuff is just garbage. They can’t perform to more than 60% of their rated capacity and then start voltage sagging. The energy density is pitiful. A small UPS under your desk with LiFePo4 cells would outperform the lead acid 3-4x for the same space and last longer for the same or less money.

The majority of the are designed for massive amounts of current for short period of time?

Considering we ship 1.2B Smartphone, 300M Tablet, 150M Laptop, 100sM of IOT Gadget, along with Electric Cars and Buses. I am very much surprised Lead Acid Battery has a higher market revenue. Apart from ICE vehicle ( Which I dont buy every year ) I dont have any Lead Acid Battery around me.