There is another dimension to this, which is the rhetoric or blaming the overseas tech companies and thereby attempting to frame this as big, rich, multinational corporations fighting against the UK. They are trying to instill an 'us-vs-them' mentality, with the absurdity that 'us' is the UK people and the UK government and 'them' is the easily-hated power of 'big tech'.
In fact, the opposite is far closer to the truth - it's the government vs the people with the tech industry, taking a stance that is for the good of people.
Sure, most of these big tech companies are doing it for selfish reasons because they are worried about losing business but that's fine by me - that's how the free market is supposed to look: companies that offer services people want make a profit and prosper while those who don't lose money and fail.
The reason is, really, beside the point - in opposing the government, it's the tech companies taking a stance that protects the people overall and in the long term.