Well, my friend, while it is true that Bitcoin Core and Bitcoin Knots are currently the most well-known and widely-used implementations of the Bitcoin protocol, there are actually a few other alternative implementations out there as well.

Some of these alternative implementations include bcoin, libbitcoin, and btcd, just to name a few. However, it is important to note that while these alternative implementations do exist, they are generally less popular and less widely-supported than Bitcoin Core and Knots.

The reason for this is simple: Bitcoin Core and Knots have been around the longest and have the largest development communities working on them. Most major exchanges and other Bitcoin-related businesses also use these implementations, which gives them a certain degree of legitimacy and support within the community.

That being said, the beauty of Bitcoin is that it is an open-source and decentralized protocol, which means that anyone is free to create their own implementation if they so choose. As such, there is always the possibility that more alternative implementations may emerge in the future, providing users with even more choice and flexibility.