I've been playing synthesizers since they first came out several decades ago. They still need electricity and amplification, and I still don't like the sound for traditional folk music as well as I like the guitar. Besides, I'm a really good guitar player, just not as good as I am a keyboard player. Also, synthesizers sound a lot more like synthesizers than they do like "real" instruments, both in the actual sounds they make and in the nuances of how of the instrument is played. That said, there are synthesizer and drum machine tracks scattered through most of the nominally acoustic folk albums I've made. For my tastes, synthesizers can be a really good second accompaniment instrument, but rarely sound as good for the primary accompaniment, and I can only do one thing at a time on stage.

Another point is that a small inexpensive Yamaha keyboard is not going to have very good action; the expressiveness is limited. To get a good feel and really nuanced playing I prefer a keyboard with piano action and really high quality samples. That adds a lot to the weight and size (and cost). I spent many years playing keyboards in rock bands and got really tired of moving furniture. I've looked for and failed to find a 63- or 76-key synth with piano action. I'm surprised no one seems to make one as a smaller and lighter performance instrument.