The problem is that all software is designed for the computer hardware that has been built recently, if your system resources are not pretty current then downloading the latest version of something (like OpenOffice) will be an overwhelming drain on your system.
I still have many older machines running but I search for older versions of software to load on them (that were designed for the machines era) and I always make sure after I install anything that I go through and turn off everything that automatically “runs at boot”, even on my newer machines. That takes care of most of the “invasive” issues you are talking about.
OpenOffice is a Java based Office suite, it is very good but power hungry. LibreOffice is the new group that took over the OpenOffice open source project and they made some good strides in reducing the footprint but it is still Java based.
“Free” software means that advertisers are paying for the software instead of you, this is accomplished by “mining” your information and selling it to advertisers. This occurs by you installing whatever you have found and are interested in (like Adaware) and the data mining (Spyware for slang) is installed with it. Do this enough times and your internet connection becomes overwhelmed by these pieces of software that are continually communicating back and forth with their home servers that collect the data to sell to advertisers. Your RAM also becomes full with all these programs that “load at boot” so the entire computer becomes sluggish even when you are not using the Internet.
A whole lot of this can be averted by never choosing the “automatic, recommended” option when installing software and instead choosing “manual”, most toolbars and some data mining software can be de-selected this way but you never see the option if you just keep clicking “Yes”, “I Agree” and “Continue”.
I use some “Free” software but know where to look to shut down all the junk I don’t want and how to prevent my Internet connection from becoming an advertising portal, some “paid for” software also have these “Spyware” features but almost ALL Free software has it.
There is no “Free Lunch” to use an old axiom.
You can often google the name of the software you are interested in with the word “review” and find out what people are saying about it, you can sift through what you find and look for the reviews that sound like the author has some idea how all this works and ignore the ones that obviously are written by people who are pretty clueless.
This can help alot in determining whether a particular “Free” piece of software is something that you will get some use out of or just junk up your machine.