Reading is so hard...
Now if you want to discuss the actual point I brought up, then I am all ears.
Sorry, but in my defense I was between periods at school and couldn't find a TL;DR.
Secondly, I think you meant obsolete
Finally, I both agree and disagree. When you're balancing something, often you want a feeling of increasing importance. By this I mean like how in RPGs, you at first can only deal 5 damage per hit, but later you can deal 50. The amount of hits needed to kill a foe for the most part doesn't decrease with this however, and usually even increases. But the fact that you can now OHKO that boss that used to take 5 minutes makes you feel like you accomplished a lot. Even the -500 when you unleash your ultimate attack does.
Likewise, at first when you're using auto-mining, you may only get 1 iron per tick. (Let's call it IPT) But later you are get a new mining machine that can mine 10ipt. This makes you feel accomplished. And while you may be using 20 iron for your machine's drill every 10 ticks as opposed to the last tier's 2, you're not getting any more efficient.
Basically, some games purposely make some items obsolete to make sure you always can improve.