You don't actually need it to use that much RAM. It's more about memory bandwidth. An attacker can increase the memory bandwidth by using block RAM like in an FPGA or on-die RAM in an ASIC, but both of those are far more expensive than discrete DDR DRAM modules. So with appropriate memory usage (enough to saturate the cache lines) it can be cheap enough for the server to run yet still more expensive to build an ASIC platform for. Of course an ASIC can use DDR as well, but then it's stuck with the same memory bandwidth as the DDR module and gains no particular advantage.

Argon2id with t=3, m=92MiB, p=1 should be slower than bcrypt with cost 12 on most modern GPUs. That's not actually all that much memory, you can handle quite a few concurrent logins on a server with those settings. 10 concurrent logins per GiB of RAM dedicated to the task. And it should only DOS the login process, so it might make taking out your auth process (or server) easier but won't necessarily harm any other part of the site.