From the article they mentioned that has a nuanced outlook: “While there are potential welfare impairments with indoor restrictions, a number of enrichment strategies have been suggested for counteracting these effects to promote the health, affective states, and performance of natural behaviors of indoor cats. Further research is needed to assess the efficacy of these strategies and to determine whether the welfare of cats is impaired by restriction. To develop effective educational strategies aimed at reducing the impact of uncontrolled outdoor access for cats, further research is necessary to improve our understanding of owner practices and attitudes towards outdoor access for cats.“

Pet owners that are responsible should be enacting enrichment strategies to keep them happy and healthy. Further research is needed to conclude strategies are effective, but I’m not sure the conclusion is no pet cats for all because “cruel”. My anecdotal evidence points to the strategies being effective, at least.