Rav Chaim Kanievsky was a great person, a great talmid chochom, and a great leader, whether or not he actually held any official leadership position. Rav Kanievsky lived simply and humbly, dedicated to learning Torah. Rav Kanievsky was not a scam artist, he was not someone who raked in millions taking payment for brachas and taking cash in envelopes for advice and blessings. Rav Kanievsky was seemingly untarnished in that way - he just had no need for it, no interest in it and no use for it. He did and said what he believed, and nobody could think he was bought off or had other interests leading him astray.

Any complaints or anger directed at him was really misdirected. Sure, people can argue or think his opinion was wrong, but a difference of opinion is not usually what makes people angry or full of hate. I don't think Rav Kanievsky is one who could be hated - nobody would have a reason to hate him or be angry at him. Any anger at him was really anger at his gabbaim, his handlers, his followers, his community who at times perhaps misconstrued what he was saying or led him astray with partial information to prompt specific public statements or by people, in his family or otherwise, who might have benefited from their connection to him in various ways... 

People don't like when something is sold as holy but there are really agendas behind it. Rav Kanievsky had no agenda. Nothing other than Torah. The people around him might fairly be accused as having agendas, and any anger or hate, not just now but throughout his life and leadership, was really at those agendas and the people behind them, not at Rav Kanievsky himself.

(one example would be in the hespedim the speakers spoke about how he didnt even know the names of the streets he walked on to go to the shul or to get places near the house because he was busy learning and the names of the streets were not on his mind - so did he really know what a smartphone is? yet he spoke out against smartphones because his people told him how bad they are. He trusted them, but it was their agenda, not his.)