And who do we take off for Defoe with 20 to go? You can't take off Modric - everything goes through him. Take off vdV and half this board would be up in arms. Removing Lennon leaves the team unbalanced. Sandro was our main ball winner and back-tracker, so remove him and you aren't guaranteed possession, and he played the ball forward all day today.
Besides, your call for Defoe to come on with 20 to go is a different argument to the one others are making, which is that it should have been Defoe not Parker that came on...but that was on 89 minutes, not 70 minutes.
So we now have 2 different versions of the apparently obvious thing Harry should have done with Defoe, and neither of them fully explains what the team would look like after either change. There's a fundamental lack of clarity on what exactly the people complaining about today are saying.