If an illness brings anyone to Christ, you'd think that at least one of the first topics of conversation with Him would be about that illness bringing them to Him. But I think it's the generally accepted assumption that Paul's thorn was an illness that God 'wouldn't take away (which they interpret as "wouldn't heal") that causes all the stumbling. Imagine if Jesus had told the woman that came to him after suffering 12 years, "Yep, that's exactly what was intended to bring you to Me, now carry it forward for a reminder of Me."
Let's back up a bit to the event that blazed the trail for Pentecost
Matt 27:50-51
When Jesus had cried out again in a loud voice, He yielded up His spirit. At that moment the veil of the temple was torn in two from top to bottom.
Luke 23: 45-46
The sun was darkened [at noon] and the veil of the temple was torn down the middle.
Then Jesus called out in a loud voice, “Father, into Your hands I commit My Spirit.” And when He had said this, He breathed His last.
Mark 15: 37-38
But Jesus let out a loud cry and breathed His last. And the veil of the temple was torn in two from top to bottom.
John 19: 28-30
After this, knowing that everything had now been accomplished...He said, “It is finished.” And bowing His head, He yielded up His spirit.
And from the Psalm of the Cross, Psalm 22:24
For He has not despised or detested
the torment of the afflicted.
He has not hidden His face from him,
but has attended to his cry for help.
The veil was torn so that anyone could enter into God's Presence, not just the apostles, and finishing the Bible wasn't the primary reason as the Holy Spirit was poured out on all people. Joel 2:28; Acts 2:17 It was written so that all who read it might believe what is written.