Ramakrishna Mission is a organization founded by Swami Vivekananda. In their centers they only have,what they call "Holy Trio"( Ramakrishna-Sarda-Vivekananda) but not any Hindu deities. Sure, they DO worship deities on occasions such as Krishna on Janmashtmi, even jesus on christmas. But even then the main focus is on the holy trio.
When Swami Vivekananda was asked about the difference between Ramkrishnaites Hindus and Traditional Hindus,he answered that only one distinction exist i.e the ramkrishnaites don't believe in birth based caste system.But traditional Hindus, though revere their Gurus,they also worship Vedic deities,but such practice is absent in Ramakrishna Mission centers.This makes one wonder if these changes were made after Vivekananda departed.
Now in another question I asked if RamaKrishna Mission considers itself a Hindu organization which references to an infamous court case in 1980s when Ramakrishna Mission tried to separate itself from Hinduism legally.They gave various theological differences including their claim that Ramakrishnaites consider quran and bible as authentic(giving Ramakrishna practicing islam and christianity as a reaskn) as Vedas where as Traditional Hindus only consider Vedic Scriptures as authentic,among others.(Sources are available in the question above).
Doing some research about this I only managed to find a quora post. This quora post has an answer which explains that for Ramakrishna Mission ,
Ramskrishna is Vishnu, Sarda is Shakti and Vivekananda is Shiva.
In the same answer it is said that,
It is also pertinent to note here that after Ramakrishna's passing away, Sarada Devi who gave Mantra Diksha to countless disciples would initiate them to appropriate personal Gods (like Krishna, Devi, Shiva and so on) based on their tastes and samskaras. Even other direct disciples like Swami Brahmananda used to give Mantra initiation on different personal Gods during their times. It was only in later years that Senior Monks of RK Mutt who were empowered to give Mantra Diksha restricted initiations to devotees with Ramakrishna Mantra only. On account of such developments, RK Mutt did get some criticism from closer circles that there was a tendency to narrow down Ramakrishna movement to a cult.
Now I know that quora posts are not really a good source but this might point to the direction that these changes of not worshipping Hindu deites(or giving Mantra Diksha of Vedic Gods) and increasing focus on holy trio(Ramakrishna in particular) might signify the organization trying to distinguish itself from Hinduism due to the case referenced earlier( in my another question) which was done AFTER Vivekananda's departure.
So my question is, why no Hindu deites are actively worshipped in Ramakrishna Mission centers? Is this an old practice or a newer one (post-Vivekananda) in order to show themselves as separate from Hinduism?