select similar is quite a good option when you forget to group stuff. it can function like this:
for Lights, it can select those with same settings, basically those we want to consider instances.
for objects, it can select those we can apply make unique to them, basically those with same material.
for special objects, like characters, pets, etc, it can be just select all of them.
it really can make a difference.
Working on large landscape models can be challenging, especially when it comes to placing and updating large quantities of trees. 
That’s why tools like ‘Select Similar’ are essential! They make it easy to swap tree types across a model in no time.
I know the function. But with the object browser function is possible you only need to know it. Ibwanted to select all spot light today. Filter made on lights and than slect al spotlight. And i flipped on caustic.
If you have an object you can also search in the object browser.
The functionality is there, only in an diffrent toolset.
It’s true that using filters and search function can help a lot, but select similar is a quality of life improvement that can ease your mind. One right click and then one left click is much faster than seaching 