One can cut a slot if one wishes — and it’ll work once or twice, or a dozen times, but one day, it will fail — maybe if one adjusts the feeds and speeds and Depth per Pass one can make it somewhat reliable, but not cutting a slot is viewed as best practice on a machine which lacks any sensors to determine if a step has been lost.
It’s workable on a hand-controlled machine because the operator can listen to the cut and feel the machine through the control and adjust the feed rate and so forth.
It’s workable on a machine w/ closed-loop control because it will know the machine’s position and adjust the commands to the machine accordingly, though if it work-hardens a section of the stock and breaks a tool, that is a "bad thing"™
It’s not workable on a machine which doesn’t have sensors to know where it is, and which sends movement controls and has to have confidence that each step of the stepper motor which was requested has resulted in the expected machine motion.
Where possible avoid slotting and add geometry and cut as a pocket
and/or
and consider leaving a roughing clearance and taking a finishing pass.