They still are, wherever people work with animals at small scale. People get attached, and the boundary between "animal as my fellow (if dumber) friend" and "animal as my main capital investment" gets really blurry. This was the reality for most people until 20th century, and we still see echoes of that in old books and stories.
This sounds like a clever argument, but the mindset of some executives really has no impact on how differently horses and humans are treated in society.
To spell it out:
When horses are no longer needed for a task, they are sold or sent to slaughter.
I hope I don't have to explain how differently you and I are treated when we lose a job?
People need jobs in order to pay for food, shelter, and healthcare.
Many executives feel zero moral obligation to provides jobs to people and instead treat that as a necessary evil that gets in the way of profit. As soon as that evil becomes unnecessary, they will happily lay off as many people as they can.
In aggregate, when enough executives do that, then people will not be able to find jobs.
When they can't find jobs, they are unable to pay for food, shelter, and healthcare.
I don't disagree. Trajectory has overall been great for people. Just saying it's not uniformly great for everyone at all times, in fact whenn it regularly flies off the rails, restoring it exacts a great cost from individuals and societies.
It's not really "many" centuries. It's more like three or four and even that's not uniformly distributed. There are still many subsistence farmers in the world, and almost all of us were doing that for thousands of years.
Also, those past few centuries have involved the largest violent revolutions and wars in human history.
The idea of employment and money is a relatively modern conception. There is no physical law that states it must work indefinitely and efficiently for all participants.
This is exactly the perspective many executives have of their employees.