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It doesn't make mining useless. Blockchain requires mining.
But now, it depends on how you mine.
IF you check posts made on august 24th in steemchat mining channel you will see and interesting discussion :

It looks like nobody (aka supercomputing aka gxt-1080-sc-0024-nnnn succeeded to code a miner using GPU. Give a look at the witness queue and you will see it's dominated by gtx- miners.

If all the above is correct, this means that CPU-mining like you do will be soon inefficient.
Your chance to get a spot in the mining queue will be near zero :(