Why do some still quote corrupted texts...?

even though these have been proven to be NOT of or from God. Texts as in the Textus Receptus and any translation that used these as source texts, e.g. KJV?

1 John 5:7-8

New International Version (NIV)

7 For there are three that testify: 8 the[a] Spirit, the water and the blood; and the three are in agreement.

Footnotes:

a. 1 John 5:8 Late manuscripts of the Vulgate testify in heaven: the Father, the Word and the Holy Spirit, and these three are one. 8 And there are three that testify on earth: the (not found in any Greek manuscript before the fourteenth century)

1 John 5:7-8

King James Version (KJV)

7 For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.

8 And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.

1 John 5:7-8

New Living Translation (NLT)

7 So we have these three witnesses[a]— 8 the Spirit, the water, and the blood—and all three agree.

Footnotes:

a. 1 John 5:7 A few very late manuscripts add in heaven—the Father, the Word, and the Holy Spirit, and these three are one. And we have three witnesses on earth.

1 Timothy 3:16

New Living Translation (NLT)

16 Without question, this is the great mystery of our faith[a]:

Christ[b] was revealed in a human body

and vindicated by the Spirit.[c]

He was seen by angels

and announced to the nations.

He was believed in throughout the world

and taken to heaven in glory.

Footnotes:

3:16a Or of godliness.

3:16b Greek He who; other manuscripts read God.

3:16c Or in his spirit.

1 Timothy 3:16

King James Version (KJV)

16 And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory.

Revelation 1:11

King James Version (KJV)

11 Saying, I am Alpha and Omega, the first and the last: and, What thou seest, write in a book, and send it unto the seven churches which are in Asia; unto Ephesus, and unto Smyrna, and unto Pergamos, and unto Thyatira, and unto Sardis, and unto Philadelphia, and unto Laodicea.

Revelation 1:11

New Revised Standard Version (NRSV)

11 saying, “Write in a book what you see and send it to the seven churches, to Ephesus, to Smyrna, to Pergamum, to Thyatira, to Sardis, to Philadelphia, and to Laodicea.”