Thanks for your submissions and concerns.
i) First of all it is to be cleared that this website is private -independent rail info website and is not any part of Railways deptt.
ii) Your observation ... "No identity proof is required .... nor during the journey" appears on the IR website and nowhere on this website.
iii) Tatkal tickets...
more...

are like normal tickets and the difference is that of only levy of extra Tatkal charges. So for counter Tatkal tickets as such you do not require to carry any id proof but for e-tatkal tickets, similar to regular e-tickets, carrying of any one of prescribed id proofs is must and mandatory.
iv) Nowadays, in order to prevent a) touts from selling railway tickets and b) passengers travelling on third party tickets, the TTE's demand such id proofs whereever they are apprehensive of or the cirucumstanced demand such id proofs.
v) As you have rightly mentioned that .... Not on the IR website but in the ticket, it is mentioned for such id proof and hence one is supposed to peruse fully the travel requirements and hence ignorance may not become excuse under this situation.
v) This is better for improved civil society life and it's always better to carry id proof with 2-3 zerox copy - preferrably and id- photograph etc.
Make it a part of the journey kit.