Just because a few people on an internet forum are confused about the definition of the term monopoly, that does not change its meaning. Ebay still remains a monopoly.
Q: Why doesn't anybody today try to start up a new company to compete against UPS and FedEx?
A: Because these two industry giants have the market sewn up, ergo it's a loosing battle.
Same is true with Coke and Pepsi. Two industry giants selling nothing more than sugar water.