This may be a contradiction. Weibo, with its high degree of freedom, has been purifying its own content. Now it is the period of ICO decline, and they may be the most sensible to do so. As a social software, you must be responsible for the user.
Twitter is not fighting cryptocurrency advertising, they are fighting the scam crypto ads, there has been a lot of twitter addresses that was confirmed with blue tick that got hacked recently and all of that was used for getting people to send money somehow. The hackers that gets those type of twitter accounts manages to change the name to something like elon musk and than use it to tell people send ethereum to their address, a lot of people believe them somehow and one even got away with over 200k thousand dollars recently. Twitter is trying to find a way to fight that and stop advertising false scam ads on their platform. In order to do that they have their security department banning all risky ones which means sometimes the real ones get banned too.