Have you ever started work one day and thought “oh dear it has been a while since we updated any of our npm packages”, or maybe the warnings that show during install have been building up, and no one is really taking the time to understand why. You also might find out one day that you can’t make that React major version jump because many of your packages are on old incompatible versions. You could also be shocked to realise that you have 12 security vunerabilities because of outdated packages. None of these scenarios are good.
Tools like dependabot and renovate can help. They will automate the actioning of package updates which means these updates are much more likely to happen in a timely fashion, instead of building up and causing negative impact. Both of these packages have full Github integration so there really is no excuse in not using one!