As per I know i think the text object are much used for the actions they have and replaces the Buttons.
Where as text objects can be used for the text notes and and messages place holder but not the Buttons.
Buttons provide much clear design and look as compared to text.
May be the memory level values differ for the two.
As per my knowledge Text objects are more used than buttons, both have almost similar feature except the look and feel. The Clickable action in the text object may not to so user friendly where as in the button you have the action look and feel..... Text object you can add text msg where as in the button it might not look good.
So based in the requirement both has its own advantage and disadvantage
The advantage for a Button is that it has an Enable Property. You can use an expression in the property to make the button disabled (grayed out but visible, not clickable) or enabled.
The text object has more options for styling. The Enable equivalent for a Text Object may be to make the object invisible using a Show Condition, but you lose the visibility as a hint. You can style the Text Object to appear "grayed out", but you can't suppress the Click Action like you can with a Button.
If I want to use the enable/disable action metaphor, I use a button. Otherwise I usually prefer a Text Object for the richer styling.
One other obscure difference is the default Layer property. Buttons are assigned "Normal" as they are reasonably anticipated to be combined with other objects such as charts. Text Object are assigned a default Layer of "Bottom" which can make them disappear when combined with charts. Like I said, obscure difference because you can always adjust the Layer to fix the issue. But it feels that Buttons seem to assume their rightful layer automatically.