A few years back I butted heads with a system administrator over SQL Server database backups. He wanted to use a 3rd party backup tool to perform the backups. I did not. If you're a DBA, you've likely had that same battle yourself. When you're in charge of things like DR, RTO, RPO, etc., it's a bitter pill to swallow to cede control of the database backups to someone else and/or lose control of the backup processes.
I've also had dealings with vendors peddling their own proprietary monitoring software. I find it curious that these organizations provide software that can monitor systems running on a multitude of operating systems, not to mention multiple RDBMS's--all while positioning themselves as experts at everything. 1 I've been using SQL Server for 15+ years and I'm still not comfortable calling myself a SQL Server expert.
3rd party SQL Server tools are training wheels. They're meant for sysadmins or accidental DBA's. And that's fine--there's nothing wrong with that. But I'm the wrong target audience for most of those tools. Why? Because they're superfluous and gratuitous. When you devote your career to SQL Server, you learn a few things here and there. You can't help but notice the commonalities among 3rd party tools. They usually do little more than leverage existing functionality that is native to SQL Server, wrapped in a GUI, and marketed as a sparkly unicorn that no one else has discovered. Please.
Is there anything you can't do with SQL Server Management Studio? Perhaps. I've certainly augmented SQL Agent Jobs with a PowerShell script or two over the years. I've even used VS Express to create console apps used in job steps 2 You could make a strong argument that this is a developer task though, not a dba task Maybe I'm different. Having a development background, I'm as much a producer of code as I am a consumer. Being stuck with 3rd party tools is restrictive, sometimes to the point of preventing me from doing my job. Why would I embrace this?