I looked into this a couple months ago and external TB5 was still more expensive at 1-2 TB not sure about above, though.

Going from 500GB to 2TB built-in is €600 in the US at the moment.

Samsung 990PRO 2TB is $170 and Acasis T5 80Gbps is €300. So it makes sense to buy external for ≥ 2TB, more flexible as well :-)

For 1TB it makes more sense to buy built-in as you note above.

It also depends on the quality of that enclosure and whether or not it adds heat or fan noise.