Back when I joined iSpot (2007/8 ish) I discussed this with the then iSpot team and it was a a deliberate decision. With no way to directly and privately contact members it was thought it would be safer for allowing children to access it and that parents would be more comfortable letting them do so. As a key part of iSpot’s purpose was supporting people just starting out learning about natural history this was seen as very desirable. Personally I feel it still is.
I’m not sure I see a value in a personal contact option here (and there has been at least one individual in the past who I am very keen has no method of contacting me in person) since it is focused on identifications and they work best done in public.