Yes they are. There were tons of people waiting to leave Twitter for something better. What makes Threads the better alternative is they already have Instagram accounts and so does everybody they know. Joining Threads took me 30 seconds.
It seems obvious because they literally said that’s what they’re doing. They’re not trying to hide it.
If you have an Instagram account, it literally takes a single click to sign up for Threads. Your Instagram account is the same as your Threads account.
It’s like how your Gmail account is the same as your Google Drive account.