A monopolist has no reason to decrease price because there is no competition. As we saw with Bell Labas in the US it is entirely possible for a monopoly to both have world class research and burry it for decades, viz. magnetic storage https://gizmodo.com/how-ma-bell-shelved-the-future-for-60-ye...

Oligopolists are in the same boat. But there needs to be a conspiracy to retard innovation. Something tech companies are only too happy to do: https://journals.law.unc.edu/ncjolt/blogs/wage-fixing-scheme...