I'm sorry to say I can't answer your specific question, but I can tell you that elevation most likely didn't have to do with whether a mountain was considered religiously significant. Jebel Aqra, a mountain on the coast of Syria, was also considered to be a sacred mountain and home of Zeus and this mountain is only a little more than half as tall as Olympos. I would wager to guess that sacred mountains of this type had more to do with local superstitions and stories than "my god has a bigger mountain than yours!"

In Jebel Aqra's case, the mountain had a long tradition of being considered home to a storm god. The first we know of is the Hurrians' Teshub, who was adopted by the Hittites. They both called the mountain Hazzi, and the Greeks later adopted this name upon contact with Neo-Hittite kingdoms in Syria and called it Mt. Kasios, which became the mountain's name for a very long time. The local Greeks paid tribute to Zeus Kasios, and even rulers such as Seleukos and Trajan went to its peak to worship him. It's pretty obvious the Greeks of the region syncretized native religious beliefs about the mountain. They did this a lot around the Mediterranean.

Another example is Homer's Mt. Ida, now known as Kazdağı and located near Troy. In the Iliad, this is where the Gods gather to watch the war. Mt. Ida is not even close to as tall as Olympos. In antiquity, this mountain was said to have been sacred to the mother goddess Kybele, who laid claim to numerous other mountains in the area.