And many of these same people probably (and rightfully) laughed at music and movie people casting piracy as “theft”.
It is irrelevant whether the thing or feature you took away is implemented in hardware or software. Notably it is often hardware functionality but the thief uses software to restrict it.
You could perhaps argue that another property crime might better describe it such as criminal mischief or in some cases fraud. But in any case it is a crime against someone else's property.
Is it theft if a company stops supporting TLS 1.0 clients that were previously supported?
What about upgrading service to only support a new form of authentication, breaking some clients?
What if the new authentication can only be done by locked down official client?
What if the company never advertised support through third party clients?
It’s wrong for sure, but I’m vicariously embarrassed for those who want to define everything they don’t like as “terrorism” or “theft” or whatever, strictly because it sounds so dramatic and casts the wrongdoers as not just wrong, but evil.
It’s old, it’s tired, it doesn’t convince anyone.
Simple “failure to adhere to terms of sale” is sufficient, and doesn’t have the baggage of being false.