Jacob
What goes around comes around.
The DIY sawboard is good for top side clean cuts as it is effectively a zero clearance fence Sawboard - DIYWikiYou still get a chip free cut on the underside without a sacrificial sheet below because the teeth are cutting upwards in to the material, it's like a jigsaw, clean cut underneath breakout on the top.
If there was any chipping it would be on the top face where the teeth exit the cut but the plastic zero clearance strip on the track stops this.
People often put a board under because it improves dust extraction.
They are actually very good - much better than you might expect.