Yes, the same concern exists for Synthesia. It teaches a significant amount of muscle memory.
But that is not such a bad thing:
* Muscle memory is part of the game, for any instrument (at least for the ones I know).
* Some of the muscle memory is transferable. For example, when you learn some chords on Synthesia, you can transfer many of them to other parts of the keyboard, also when you're not using the tool.
* For many people, motivation must come first. Learning a piece by muscle memory shows you that you can do it. Wanting to read sheet music naturally follows, from the fact that muscle memory is limited, and to play more stuff.
* Synthesia also teaches rhythm, which some people already have but others don't. You can learn rhythm because Synthesia shows how long each note is, and you can see it coming ahead of time.
* You should learn to read music notation in all cases. Learning the concept only takes 30 seconds: Remember where one note is and do the rest by line counting. The speed of reading will come automatically over time. Then for some songs, enable Synthesia's sheet note display and cover the falling notes from sight. It will show you whether you're reading it correctly. It'll be painfully slow at the beginning but improve over a couple days. It allows you to transfer over to just reading the sheets. Eventually that will become the more convenient way, as the need to download (e.g. from MuseScore and import into Synthesia) disappears; not that it's great effort, but eventually you can just browse easy pieces of sheet music and start playing the ones you like as you see them.
Tools like Synthesia help improve on some of the skill axes; use other methods for the remaining ones.
But that is not such a bad thing:
* Muscle memory is part of the game, for any instrument (at least for the ones I know).
* Some of the muscle memory is transferable. For example, when you learn some chords on Synthesia, you can transfer many of them to other parts of the keyboard, also when you're not using the tool.
* For many people, motivation must come first. Learning a piece by muscle memory shows you that you can do it. Wanting to read sheet music naturally follows, from the fact that muscle memory is limited, and to play more stuff.
* Synthesia also teaches rhythm, which some people already have but others don't. You can learn rhythm because Synthesia shows how long each note is, and you can see it coming ahead of time.
* You should learn to read music notation in all cases. Learning the concept only takes 30 seconds: Remember where one note is and do the rest by line counting. The speed of reading will come automatically over time. Then for some songs, enable Synthesia's sheet note display and cover the falling notes from sight. It will show you whether you're reading it correctly. It'll be painfully slow at the beginning but improve over a couple days. It allows you to transfer over to just reading the sheets. Eventually that will become the more convenient way, as the need to download (e.g. from MuseScore and import into Synthesia) disappears; not that it's great effort, but eventually you can just browse easy pieces of sheet music and start playing the ones you like as you see them.
Tools like Synthesia help improve on some of the skill axes; use other methods for the remaining ones.