There are actually a lot of "this is Troy" signs pointing to the city, though not literal ones. The ancient Greeks were super duper clear that the site we now call Troy was Troy, and they wrote about lots of famous people (Alexander the Great, Persian Emperor Xerxes) visiting it. There were even temples at the site existing into the Roman period, which we can still see the ruins of.

The area's topology is also incredibly consistent with the place Homer described, and it was described as being in the location where it is near Mount Ida (now called Kazdağı in Turkish). The site is also described as being relatively close to dozens of Greek cities named in the Iliad and Odyssey, many of which we know were called by the same names as far back as the Mycenean period. We also have records from the Hittites describing their political relations with the polity they called Wilusa, which is a cogate name to the Greek Ilion (the main name for Troy, which you can see in the name of the Iliad).

There's just a ton of circumstantial evidence here, so much that there's no reason to think anything else. But one thing that a lot of popular historians like this Wilkins fellow don't seem to understand is that the Iliad and the Odyssey were essentially Greek stories written during and mostly about the Geometric and Archaic periods, not the Bronze Age. We can see reflections of the societies Homer describes in contemporary archaeology and the writings of his peers. Homer (and his fans in Greece) certainly believed what he wrote was to some extent historical, but we know it's not. There may have been a kernel of truth to it (Hittite documents seem to describe a military conflict between Mycenean Greece and Troy), but it's not really important to our understanding of the ancient site.

To some extent, "Troy" is Troy because the Ancient Greeks believed it was and overlayed their mythological stories onto a real ancient city. Aside from epic poetry there really wasn't anything noteworthy about the place. The only way to separate this real site from the story and transport it to somewhere else (like, say, Southern England...) would be to completely ignore the historical context of the poetry written about it.

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You may find this answer from about a year ago by /u/cleopatra_philopater on Where Troy Once Stood rather helpful.

It is worth noting that scholars widely agree that Troy was a real place in Asia Minor. The argument that Troy is in Asia Minor is not a flippant and circular one as you have suggested, it's actually pretty solid - the site of Troy, both in geography and archaeological remains, matches Homeric descriptions rather well. This thread from the FAQ has much more information from a variety of contributors.