You're not considering opportunity costs and buyers vs. users.
If your senior developers can slap together something better than an expensive SAAS offering you want them directing that energy at your core products/services rather than supporting tools.
And the people deciding to buy the expensive SAAS tools are often not the people using them, and typically don't care too much about how crappy the tool may or may not be for doing the job it's advertising as doing.
No matter what it's a tax on your engineering team to keep it together. But the most brittle parts are always right at the seams. It's not as hard to sew together components when you can cut the cloth down to fit together. Who knows how it'll shake out.
If your senior developers can slap together something better than an expensive SAAS offering you want them directing that energy at your core products/services rather than supporting tools.
And the people deciding to buy the expensive SAAS tools are often not the people using them, and typically don't care too much about how crappy the tool may or may not be for doing the job it's advertising as doing.