You're quite right - it's more the 'method' than the 'material'. But there are parts of the 'method' that will be either ridiculously convoluted or - to put it plainly, niggly, that I'd rather leave it to a machine to get right - and get right time after time after time. That's why the machines were invented, repeatability.
I still can't get Mrs k_e to stop boiling the @rse out of the kettle when she makes
instant coffee - the 'scalded' taste is awful - yet even showing her a properly made coffee, which she acknowledges tastes much better, still doesn't stop her boiling the water! We considered purchasing one of those dual-temperature kettles but since the issue was just 'coffee' we thought getting a machine to do the job instead.
I could, of course, make ALL the coffees myself but even Mrs k_e likes a Costa-type coffee when we're in town and considers a machine to do that as an excuse for her to purchase a McDonalds Milkshake machine in 'revenge'......

Don't take it personally......