"sinless perfection" is a misnomer applied to the doctrine of entire sanctification in order to produce a straw man argument that is easily toppled by 1 John 1:8.
In all reality, the doctrine of entire sanctification does not teach that the element of sin is eradicated from us when we are sanctified.
It teaches that it remains in us but is rendered dead (Romans 6:6, Galatians 5:24, Romans 7:8) so that it no longer has any say over our behaviour (Romans 6:14).
Again, 1 John 1:8 does not say, "If we say that we do no sin, we deceive ourselves and the truth is not in us."
Read it again.
It is speaking of indwelling sin rather than practical sins. Otherwise it is in contradiction to 1 John 3:9, 1 John 3:6, and 1 John 2:17; also all of 1 John 3:5-9.
See also Jude 1:24, 2 Peter 1:10, and 1 John 2:10. We do not have to commit sin in the practical sense.
A person can come to the point in their lives where they do not flip back to not being entirely sanctified (see Hebrews 10:14 (kjv), 1 John 3:6, 1 John 2:17).
If you want to deal with a convicted conscience every day you are alive, then by all means reject the concept of entire sanctification. If you can sin without being convicted in your conscience, then there is more of a problem to deal with there. For you are a psychopath.
But Romans 7:24 shows us that the attitude of the believer (or of one who is about to become a true believer) in a Romans 7:14-25 lifestyle is that he is discontented with his lifestyle of sinning.
If you have this biblical attitude, then the doctrine of entire sanctification is good news as a sound to your ear.
But if you are happy as a sinner; and if you love the idea that Christ has redeemed you from the penalty of your sins without actually redeeming you from your sins (see Matthew 1:21, Titus 2:14), then the doctrine of entire sanctification is abhorrent to you.
For you are a slave of sin and do not desire freedom; because in order to be free you would have to become a slave of righteousness. I am speaking in human terms because of the infirmity of your flesh.
