Depending on third party plugins for theme functionality

I am building my own theme (first premium theme) and I admit there is lots and lots of decision making involved. One such decision where I am currently stuck is about using open source plugins for achieving certain functionality in my theme. Most of the times the functionality we need to provide to our customers is already available in the form of plugins. And I also know it is perfectly okay to use third party code in my theme by providing appropriate license. But what I want to know is when to rely on plugins and do not reinvent the wheel. I have two such example situations where I feel that asking the user to install some plugins will be a win win.

Example 1 : Social media buttons. There are already tons of social media plugins available. If i want to provide this functionality in my theme, do I really need to create this from scratch or just using an existing plugin in my demo site will be fine? And later instructing the user to install that plugins via TGM or other methods.

Example 2: I want to provide infinite scroll functionality and Jetpack already has a great module for that. All i need to do is add_theme_support. Again the question is same.

I am a new developer and working on my first theme. Therefore I don’t have much courage to make these decsions. Any motivation or good advice will be really helpful for me.