And swiping a button 1400 times sounds a lot easier than swiping it 500,000 (although of course, one could outsource it to a click farm if determined).
I'm not saying it's impossible.
You can program your computer to sign them all and he'll do that in few minutes (or more) I agree swiping 1400 is ridiculous but you can do without that. As you said it's just for fun
There are doing that for stress test I believe, they have programs and we get huge blocks But maybe you're right and it's hard to propagate lot of small txs instead of few big ones