Question: I find it easier to use SSHFS to mount a remote file system on my local computer instead of plainly SSH'ing into the remote computer. This saves me from using all the complicated `scp` commmands for copy/paste. But on the internet, I find very few people talking about SSHFS. If SSHFS is more easier, then why isn't it more popular? Are there any disadvantages to it?

Answer: 
SSH is not primarily used to copy files. It's used to log in to and operate remote machines/server via a secure link, and create secure tunnels between hosts. It's available (or can be installed) on pretty much all the main operating systems out there.

SSHFS is limited to remote mounting, available only on systems that have FUSE available - it doesn't serve the same purpose. `scp` isn't really complicated, it has similar syntax to its "predecessor" `rcp`. If all you need is to copy one or two files, `scp` is just fine. You might also be interested in `sftp`.
Compression overhead, poorer low latency toleration and memory hungry and if connection cuts every now and then sshfs can get cranky.Typical tradeoff when using a secure (sshfs) versus an insecure (nfs) protocol.