Help with HRA rules for tax

Hi people, tax season is here, I need help with HRA rules. Hi , I need your help in understanding HRA for tax calculations. As per old regime, HRA is calculated as minimum of: a. Actual HRA received b. 50% or 40 % of basic C. Actual rent paid -10% of basic My question is why isn't complete rent paid annually is not considered as tax exempted regardless of any clauses? The entire rent I pay is an outgo for me and income for the landlord. If I calculate using above 3 conditions , my exempted tax amount will always be lesser than the actual rent I paid in a year. So why total annual rent paid is not considered exempted? It's like I am paying 100rs for something but getting tax benefit only on 70rs. Is there something that I can do about it?