Adoption was at 1.5% -> therefore adoption increased by 100% relative to its former value. That’s totally reasonable. Saying it increased by 1.5% is what buries the lead, because you have no idea if that’s a major or minor increase. Doubling is major.

First of all, nobody expects Linux to have much of market share in gaming anyway, so I don't know who would think that a 100% increase is somehow not "preparing expectations". Unless someone doesn't undersand how percentages work, I guess.

Secondly, I specified what kind of increase it was.

It's huge. Imagine if news said that 1,5% of people had recently switched to bycicles for their commute. What would your reaction be?

1.5% to 3% is a doubling (100% increase). It's not 1.5%, but 1.5 percentage points. It's a very normal use of percentages