This blog post is pure nonsense. Nobody can alter an Ethereum smart contract unless they control all full nodes, or can convince all full node operators to install a fork of the software that reaches into the database and modifies that contract.
It is possible for smart contracts to contain code that allows them to update themselves when receiving a message signed by a certain key, but if this is the case, then it is obvious to anyone inspecting the contract.
Most heavily used Ethereum contracts such as Uniswap and Compound for example do not contain any updating code because users do not trust it.
I read quite a lot of smart contract code, both on Ethereum and Binance Smart Chain. It seems to more common on BSC the deployment using the upgradable proxy pattern. This is probably because is more attractive to incoming devs (lower fees, faster) and this seem to be encouraged in tutorials and such.
Upgradeble proxy contracts with an active admin completely change the premise of a decentralized service. At that point it's just using the blockchain as a database, which is the worst choice of db for a centralized service
Compound had a huge bug which lead to the CEO (lol decentralized) to threaten users that got the airdropped tokens he will report them to the IRS. This is decadence at the highest level of this "new era".
It is possible for smart contracts to contain code that allows them to update themselves when receiving a message signed by a certain key, but if this is the case, then it is obvious to anyone inspecting the contract.
Most heavily used Ethereum contracts such as Uniswap and Compound for example do not contain any updating code because users do not trust it.