https://fasterplease.substack.com/p/cathedrals-or-computer-chips-which

But I think there’s more to it than that. In the lively and readable A History of Christianity, British historian Paul Johnson explains how the common believer interacted with the grand cathedrals of Europe that, I found out, were largely inaccessible to common believers. Cathedrals mainly served the clergy, wealthy patrons, and the upper classes. The emphasis on relics, commemorative masses, and architectural grandeur further distanced them from the spiritual needs of ordinary people.

Johnson: 

Indeed, it is hard to see the cathedrals as serving Christians as a whole. They were built essentially for the clergy and the upper classes, and to some extent for well-to-do townsmen. … The laity had no part in the services, and indeed when they stood in the nave (which had no benches or chairs), the high altar would be obscured by the screen or pulpitum. Sometimes no nave was built at all, as at Beauvais. Usually, it formed a vast vestibule for the choir, used for professional purposes. It was not intended for lay worship except where, as in a few cathedrals, building it had involved knocking down a parish church. Then an altar would be set up and function. But most naves were big, empty and dirty places, not elaborately decorated like the ‘clerical’ part of the building. … 

In some cases the public could get into the transepts. More often these and other parts of the cathedral were filled up by chantry chapels, paid for from the wills of wealthy people for the saying of daily masses for their souls, and to which only the donors’ families were admitted. Chapels gradually occupied all the empty space, together with extra altars for the saying of masses for the dead – these, too, had to be paid for.   … 

Then, in 740, the papacy decreed that archbishops might be buried within their cathedral, and thereafter the rule was broadened until from about 1250 it was a matter of cash – thus the rich and well-born cluttered up the interior. Over this ocular assertion of the fact that money might count in the next world, as well as in this, soared the dramatic battlements of the edifice, the needs of stone architecture – stone progressively replaced timber – to a large extent dictating shape, while size became, as it were, an arrogant assertion of the power and distinctiveness of the clerical class, and of their lay benefactors whose bones were housed below. … No wonder; an analysis of the building, growth and functioning of the cathedrals explains many of the reasons why the Reformation occurred.