The answer seems to be simple:
The most characteristic speciality of RG is its scoring system. This scoring system is determined by an algorithm based on some not sufficiently modelled and assessed objectives which oscillate in their impacts. This oscillation means for many of us as an uncountable deformation and the source of uncertainty.
Participants are “measured” on the basis of up votes granted by peers. The objectivity of this up votes cannot be the subject of this evaluation.
Where can get a lot of up votes? Where there is a big traffic! Big traffic = a very high audience. Thus, the question should be very general, without needing deep and specialised knowledge and practically no or very little looking for references and other preparations.
Specialised and strictly scientific threads do not attract many participants and because of economising time and risk many do not comment them. Even there are strictly scientific threads where the answer itself is important and participants do not score at all.
Thus, because of score number is determining and central this is which motivate participants.
In addition: participants do not know how the up votes are transformed into RG scores. This is certainly a willingly built up uncertainty into the system which stimulates intensive traffic and participation but not the merit and quality of threads and answers!
I think the inconvenience of scoring system has a imperfect feedback which pushed RG activity on a not wanted orbit and an originally scientific forum converges towards a Face book like system.
Addition2: Score collection became an addiction for many of us and valuable time is wasted for often superficial and over-sophisticated chats.
Your opinions are appreciated!