While it's not terribly uncommon for small hobby machines to depend on software limits I can't think of a single instance in my years of maintaining "real" production CNC machines of encountering a machine that didn't also include hard limits.
Limit switches typically include two trip points. The first is monitored by the control system; when it is tripped the control halts execution and stops the machine. The second limit is wired directly to the servo amplifier so that, if for what ever reason, the control fails to halt the machine when the soft limit is tripped power is removed and motion is halted. Both limits are fail-safe such that if they were to become disconnected it would result in a limit exceeded condition.
Limit switches typically include two trip points. The first is monitored by the control system; when it is tripped the control halts execution and stops the machine. The second limit is wired directly to the servo amplifier so that, if for what ever reason, the control fails to halt the machine when the soft limit is tripped power is removed and motion is halted. Both limits are fail-safe such that if they were to become disconnected it would result in a limit exceeded condition.