If you are a power user this could work, although you still have to check the software before installing it. But for the average user, the one who thinks that putting the seed in a USB stick is an airgap solution (!) as he only connect it to the PC for "few minutes"... Sorry it doesn't work, at the first phishing email he will connect to wifi and update applications, or install a new one. Hardware wallet, although they are not perfect, are quite good to minimize this kind of error. At the end the solution is in the mantra: don't trust, verify.