Perhaps there is an intermediate step before a personal name is firmly attached to a location -- that of simple identification. Coming as I do from the very eponymous village of Cooperstown, may I use this place as an example. When William Cooper bought up some 40,000 acres on the west side of Lake Otsego in 1786, he established (an planned) a community at the foot of the lake, which became known simply as "Foot of Lake." Gradually, however, it became known as Cooper's Town, more as an identification than as a formal name, though certainly William Cooper (who died in 1809) had no objections to it. Among New York frontier towns of the period it was noted in America and even in Europe as having been a great success because of William Cooper's settlement founding skills (which caused him to be hired by others, often without much success, to settle areas on their behalves).

When the Village was legally incorporated by the New York Legislature in 1807 is was (as a deliberate snub to Cooper by anti-Federalists) formally named the "Village of Otsego," which remained its technical name -- ignored by many inhabitants -- until the legislature (temporarily back in Federalist control) renamed it "Village of Cooperstown" in 1812 -- the name it has since borne.

Is this not perhaps a common intermediate step: Hudson's River becomes Hudson River; Block's Island becomes Block Island; Le Lac du Champlain becomes Lake Champlain. A name used originally to identify a formally unnamed feature, gradually becomes its name. This may be especially true in English-language place names, because of the inherent awkwardness in spelling the possessive version using an apostrophe, and the oral tendency to elide it -- as Cooper's Town becomes Cooperstown. Where this elision is itself awkward, the possessive form is more likely to last. We still say Pike's Peak, but perhaps only because Pikepeak doesn't exactly sing!