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Pointing out that there are competitors doesn't change that their presence doesn't overthrow the monoculture. After all, Gecko was around for a long time and Firefox did become very popular very quickly after version 2; but realistically, it took until Apple put WebKit on iOS for any real dents to be made.
Also, I think Konqueror still uses KHTML by default. I don't know if Konqueror tracks WebKit, but I think they're rather different these days.