I’m not sure where you got the idea that it was common practice for thousands of years. In formal churches which you are used to, in relatively civilized western societies it is more common for both to be offered, but that it has always been required or that way is not accurate.
The church has existed in much of its early history, and in parts of the world THROUGHOUT its history underground... the eucharist has often been taken to those who could not attend mass itself, or if the mass was held undeground, for whatever reasons. As well as within cultures where alcohol is not tolerated.
In fact more than one martyr has died protecting the eucharist they were charged with delivering under such circumstances. The catholic church has never viewed the recieving of both the host and the blood required for communion. Only 1 is required to partake in the sacrament, and this has been the Catholic churches belief in this matter for far more than just the modern era.. it is traced back to the very beginings of the church.