Let’s not miss the forest for the trees.
The sale, distribution and operation of ASIC miners can be controlled and regulated, thereby exposing a public ledger to increased risk of censorship and manipulation.
Consider the city of Plattsburgh (New York) which has just banned Bitcoin mining under environmental health and zoning laws: https://www.cityofplattsburgh-ny.gov/CivicAlerts.aspx?AID=229. The purchase and importing of equipment from overseas must first pass customs where it can be seized, taxed, Internet Purchases | U.S. Customs and Border Protection and inspected to ensure it meets technical guidelines (which can be arbitrary) before being allowed in. Equipment Authorization – Importation | Federal Communications Commission
With the distribution of ASIC miners under control, a path opens up for mining to be regulated, where licensed operators must abide by rules drawn up by some authority. Such rules are likely to include compliance with internationally co-ordinated financial blacklists, where transactions are blocked from being mined. Frequently Asked Questions | U.S. Department of the Treasury
Even cloud mining services, located thousands of miles away from their customers, can be subject to legal challenge. For example, Genesis Mining has received a cease and desist from South Carolina. Crypto Miner Genesis Hit With Cease-and-Desist Order - CoinDesk
Finally, a crucial flaw with ASIC miners is that their competitive advantage is founded on proprietary silicon. How do we know what is really going on inside the mining chip? Maybe there’s a backdoor or even a kill switch? Plenty of people can read source code but how many can use an electron microscope?
Backdoor Found (Maybe) in Chinese-Made Military Silicon Chips - Schneier on Security, This 'Demonically Clever' Backdoor Hides In a Tiny Slice of a Computer Chip | WIRED
Personally, I believe that ASIC mining is a step on the slippery slope towards centralized and regulated mining. Anyone who cares about decentralization and fair access to a public ledger should heed the warning signs.
src: Venezuelan Bitcoin Miners Must Register With the Government