Yes, professional developers always use WordPress plugins to speed up their workflow, so they can earn more profit on their client projects. There is no point reinventing the wheel when an existing tool does the job far better.
For example, when you ask a professional development agency to build an eCommerce website, they might quote you $15,000 for the project, but behind the scenes they use the plugins to make the project more profitable for them and more affordable for you.
They might use MonsterInsights to setup all conversion tracking, FunnelKit to create custom order forms, All in One SEO for proper SEO schema setup, and so on.
This is why most WordPress plugin companies offer Agency licenses so developers can use them on client projects.