If it is a plate with a simple hole for each switch then it should be just as stable.
People make their own keyboards with that type of plate and no PCB at all.
If it is a multi-layout plate hole with wide plate hole for support of ANSI and ISO and/or PCB-mounted stabilisers etc, then I am not so sure. I have not tried it. I think there could be some play side-to-side.
Holes enlarged on the vertical axis would be worse.
If your PCB supports PCB mounting pins and you use switches with those pins (a small plastic pin on each side of the centre peg) then the switches would be even more stable.