If you were right, Pep wouldn't bench Walker, Stones, and Ake, widely perceived as top defenders, to start Akanji. He did it, and he was right as shown by the best results in our history trophies wise.
It's obvious Pep and some fans see Akanji very differently. The latter are focused on his limitations, Pep sees his upsides. Pep was right after all.
Any of our defenders has weaknesses. Ake is loved for a reason, but he was poor in 23/24 and Pep benched him due to his mistakes. Those are not remembered, as fans love him. It's how the confirmation bias works: it filters the contradicting information and emphasizes the information we like.
Many fans have a negative bias towards Akanji and are fixated on his downsides, but didn't notice when their favourite players, say, Ake and Stones, helped United beat us in the FA Cup last year. Pep started them both in the final, after benching them in the run-in, and we were 2 goals down after 30 minutes against a very average United side.