Or more correctly, it was nice to be able to put things into very low orbit, for a while. And "a while" will only be until the fragments collectively are decelerated enough by drag to reenter:
"However, even a catastrophic Kessler scenario at LEO would pose minimal risk for launches continuing past LEO, or satellites traveling at medium Earth orbit (MEO) or GEO" (from your Kessler link)
So, in terms of Kessler syndrome being an issue, it possibly could for LEO, but for a fairly short time as atmospheric drag will deorbit the fragments after a while, and in higher orbits the drag wouldn't be enough to do this, but space gets really big really quickly and the problem gets minimized from that.
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