What are the origins and history of the practice of holding massive healing crusades in large stadiums or arenas?
First of all, John Mee’s response to this question seems to be on the right track.
In our modern are this whole idea of holding any sort of religious rally, crusade, mission or healing services in large stadium actually was influenced by no other than Billy Graham’s crusades which he started in 1947.
Crusades
From the time his ministry began in 1947, Graham conducted more than 400 crusades in 185 countries and territories on six continents. The first Billy Graham Crusade, held September 13–21, 1947, in the Civic Auditorium in Grand Rapids, Michigan, was attended by 6,000 people. Graham was 28 years old. He called them crusades, after the medieval Christian forces who conquered Jerusalem. He would rent a large venue, such as a stadium, park, or street. As the sessions became larger, he arranged a group of up to 5,000 people to sing in a choir. He would preach the gospel and invite people to come forward (a practice begun by Dwight L. Moody). Such people were called inquirers and were given the chance to speak one-on-one with a counselor, to clarify questions and pray together. The inquirers were often given a copy of the Gospel of John or a Bible study booklet. In Durban, South Africa, in 1973, the crowd of some 100,000 was the first large mixed-race event in apartheid South Africa in which he stated that "apartheid is a sin." In Moscow, in 1992, one-quarter of the 155,000 people in Graham's audience went forward at his call. During his crusades, he frequently used the altar call song, "Just As I Am".
Graham was offered a five-year, $1 million contract from NBC to appear on television opposite Arthur Godfrey, but he had prearranged commitments. He turned down the offer in order to continue his touring revivals. Graham had crusades in London, which lasted 12 weeks, and a New York City crusade in Madison Square Garden in 1957, which ran nightly for 16 weeks.
After seeing the success that Billy Graham had with his crusades in large stadiums, it would only be the logical conclusion that our would start using this same technique for someone to have as you say, massive healing crusades in large stadiums or arenas.
William Franklin Graham Jr. (November 7, 1918 – February 21, 2018) was indeed the forerunner of use ing stadiums for crusades whether for distinctly preaching the Word of God or for healing ministries. He sowed the seeds.

Billy Graham on the steps of the Capitol, in Washington DC, preaching a service on February 3, 1952.
Graham often said those evangelists, many itinerant Third World preachers who taught the Bible at the risk of their lives, were his true successors.
The healing powers of Billy Graham During his ”Crusades” were most prominent during his altar calls at the end of his crusade services.
If we want to use the Scriptures, only then perhaps we should look towards Our Lord we he gave the Sermon on the Mountain, as a point of origin of this basic concept.