Learning on a transmission with >6 speeds is hard mode, they do take a little more thinking with the gear pattern than in a car. Synchro versions are not that hard if you're used to a regular manual but adding another thing to learn is not ideal when starting out. If it was a non-synchro variant then good luck getting someone to pick that up without a few solid hours of learning time.

If you were being taught by someone used to heavy trucks it makes sense why they didn't tell you to push the pedal right in - on many (all?) non synchro transmissions pushing the clutch all the way in brakes the input shaft and if you're moving you then have to resynchronise it with the gear speed in order to get into gear.

Note you don't actually have to push the clutch in all the way in a car either, all that really matters is getting it past the point where the clutch is fully disengaged. After all the clutch plate is either touching the flywheel to some degree or it's not touching, once it stops making contact pushing it further away doesn't make a difference. When first starting out though it's easier to just push the pedal all the way in - save thinking about finer details until you're comfortable with the basics.