Purpose of bolsters?

[AllenMcB]

I figure this is a dumb question, but I'm asking anyway.

I just put new handles on a small, single bade folder. The previous handles were between plastic, snap-on bolsters which had already fallen off.

I replaced the handles with full length wood scales, new brass pins, etc. No bolsters.

What function do the bolsters serve? Why are they there, instead on having full length scales?

[jonet143]

they add strength to the blade pivot.

[AllenMcB]

they add strength to the blade pivot.

Ah. Makes sense.

So, why do some manufacturers use them, and others do not? Is it just a design thing. where bolsters would be the better function, but no bolsters goes with their aesthetics?