PAF learned from its F-16 experience with different blocks bringing incremental upgrades and ultimately culminating in an aircraft which is quite lethal. They knew that you need actual flying time and trial + error to build a new platform from scratch. You can try and soothe your wounds all you like by calling this acceptance of an under developed aircraft but PAF put this strategy to use and the results have been better than they have been using the approach that HAL took.It is about requirements, and nothing more.
JF 17 is made by Chinese but they don't want because it does fit for their requirements because the have better aircrafts.
Even PAF was ready to accept a under developed aircraft from block 1 to block 2 and still now, block 2 is not have not integrated with helmet-mounted display and sight (HMD/S) system.
The same goes to IAF, definitely there was some delay but again IAF was not ready to accept as same as chinese a under developed aircraft.
HAL Tejas MK1 and JF 17 block 2 - both are having same capabilities but difference is that PAF is ready to accept but iAF is not.
Moreover, HAL Tejas MK1a and Jf 17 block 3 will be better and good aircrafts.