But is the nerf intentional?
Not directly, but the nerf enforced what mapmakers most likely intended.
The intended version was that "chance" field means "chance to spawn items here". This is easy to understand and obviously The Right Thing. So any mapmaker who doesn't experiment would probably treat it as obvious.
The old version - bugged one - had "chance" meaning two different things: when "chance" was 100, it meant "spawn this thing here". When "chance" was below 100, it meant "keep spawning until you roll a number lower than chance". So "chance":90 meant "keep rolling and spawning stuff until you hit that 10% chance to stop rolling".
Some map features may need updating now, because any mapmaker who understood the bug has most likely tried to work around it.