If your switches are PCB mounted without a plate holding them in, then yes this is true. If there is a plate, you can only open the switches if there are cut outs on the left and right of the switch. You may also only open gateron or cherry switches this way. Kailh and Outemu switches cannot be opened while soldered to a board. They have a different closing clip from the Gats and Cherry's.
It is possible sometimes to force a switch open accidentally, but you will have a very hard time putting it back in if you have a plate. The only 100% guaranteed way to open a switch on a plate mount is to desolder it from the PCB first.