I'm not sure what you mean by "transfer me to another company” but a reservation is really not necessary. In Switzerland, almost nobody reserves a seat. Just board the train and find a free seat.

PART of the normal connection is not run by SBB (=main swiss train comp.) but a kind of split-off of them, thats probably the reason. You do not need to Reserve and in fact on half of the trains (change Luzern) it is not even possible.

I’ve travelled all over Switzerland over the years, but never with a reservation.  As has been said above, just get on the train and find a seat.  

However, if you look for trains on the SBB website, it usually gives an indication of how busy the trains are likely to be.  This means that you can look for an earlier or later train that might be quieter if you have plenty of time.