depends what they're being used for......?
not a lot of weight involved, I suspect......and a board is only flimsy if someone sits on it.
As long as the base actually holds the track and scenery together, ie doesn't flex, [which a paste table doesn't], then it really doesn't matter what it's made of......given criteria for pin-holding, weight, sound absorbtion, etc.
Really, baseboards only have to be strong if they are going to take some abuse, ie get knocked about.
as for the weight they have to carry?
well, everybody on here seems to be commenting on how light these RTR locos are getting?
Paste tables themselves do take a lot of abuse, ie bashing with a big wet brush, etc....yet seem to remain fairly STABLE...which is I think what might be the nub of the matter here??
I WOULD advise that , if considering a paste table [as opposed to a box file, for example], then chose one whose top is made from plywood rather than hardboard??
[personally, I've stripped my old ply paste table...I never intend decorating again.....and will use the ply to ''sheath'' underneath, some 25mm foam insulation from Jewsons...in itself quite rigid, yet oh so light???
I shall be building only a series of smallish planks...shelf layouts, trying out various scales and gauges , even prototypes, for variety.....plus, easy to store and move when I shift abode...[ or the family have to clear out my possessions once I kark it.]