Many parents start their kids on an electric piano or inexpensive keyboard thinking if they like playing piano they'll buy something later.  Teachers have varying opinions about this - it can make sense for very young beginners as it's more about the teacher relationship and exposure to general musical ideas than actually playing piano.  The problem starts when they do become interested and compare the teachers piano to their own practice instrument.  Learning to love music is really learning to like practicing and the more inspiring the instrument the more likely they will enjoy practicing.  Keyboards are viable instruments and some are quite amazing and useful for what they do, and there are situations that make sense to own one such as needing to play with headphones or moving frequently - or playing in a band, but keyboards will never replace fine acoustic pianos - just like electric guitars will never replace acoustic guitars - they're different instruments with a different playing experience, both tactile and aural. You will rarely, if ever, see a fine classical pianist playing a concert on anything but a fine acoustic (large grand) piano. That's because they need fine gradations of tone and touch only obtainable on a quality acoustic instrument.