As the decentralization has provided with the easy access for dark web needs, it isn't abusing decentralization. It is upto the user who make use of it, even with the fiat large scale illegal activities happen than that happening through bitcoin as well other digital currencies. When one has got good in it surely it'll have negative side as well.
Completely agree with you, mate. It depends on the individual itself rather than the decentralized design of any cryptocurrency. In the same way the Internet can be used for both good and evil things, cryptocurrencies are similar. Sometimes, decentralization brings its risks as there isn't a centralized authority. Anyone can do anything to their own will, since cryptocurrencies provide freedom. While this is true, it's still possible to control the level of illegal activity with the implementation of proper regulatory measures by the government.
As such, decentralization is a double-edged sword that can either benefit or destroy you. What's important is to be responsible at all costs, to avoid many undesired situations in the future. The only thing which I consider to be an abuse of decentralization though, is the creation of many useless Bitcoin forks with the purpose of enriching the developers.
Other than that, the decentralized nature of crypto will do fine for a couple of years from now. Just my opinion