I doubt you’d notice any difference in vigor by pulling up the post, even if you damage roots in the process. Roots grow back as fast as pruned branches. So probably wouldn’t be an issue, unless you are dealing with something like crown gall, which is made worse by damaged roots.
Hillbilly makes a good point about leaving the T-post blade out of the ground, if you want to minimize root damage.
Another solution would be to beat the blade off with a hammer before you drive the post, so the blade won’t grow under the roots. Btw, don’t try to pull the posts by hand. Too hard on your back.