afaik that's +VAT and also for LIRs only. LIRs apply markup, see https://www.lir.services/lir-sponsoring/ they charge 200€ per resource, so ASN + PI would be at last 400€/year that's way above the price of ARIN and you have a middleman.
You must have a sponsoring LIR for your resources or become a LIR yourself. The only exception is LEGACY resources (IPv4, no ASN) but that's a different story.
There are more competitive LIRs out there. Example: https://lagrange.cloud/products/lir
It’s also cheaper for me because I have legacy ARIN space. All I really needed was an ASN. The LIR gives me some PA v6 space for cheap, too.
Okay, but that is not enough to operate independently. PA v6 is another dependency. With ARIN you get your personal IPv6 assignment.
For a hobbyist, the difference is academic. You can announce PA space with your own ASN, which is what I do. If I change LIRs I’ll have to renumber my IPv6 space.