I don't want to get into a whole thing about this, but technology and software march on.
Companies that put out ANY type of product, to sell to the public, is going to keep producing something new every single year to stay in business and to be profitable.
Technically, anything you purchase in a given year WILL be obsoleted with a “new and improved” model the following year.
Nothing has been "intentionally” removed from your Mac.
The computing hardware and software requirements improve yearly and, eventually, those requirements exceed the capabilities of older hardware and software.
That's the reality.
“Nothing is forever!”
This is all I want to state/say on that topic/issue.
Anyways, since you hadn't acknowledge my concerns about being online, or not, with using a very old version of Apple Safari, you should seek out a third party web browser to use on the Internet that is more recent and more secure.
Also, before embarking on a major OS upgrade, it would be wise, advisable and very prudent if you have a good, working backup of your current system to an external connected and Mac formatted Flash drive OR externally connected USB, Thunderbolt or FireWire 800, Mac formatted hard drive. Then, use either OS X Time Machine app to backup your entire system to the external drive OR purchase, install and use a data cloning app, like CarbonCopyCloner or SuperDuper, to make an exact and bootable copy (clone) of your entire Mac's internal hard drive. This step is really needed in case something goes wrong with the install of the new OS or you simply do not like the new OS, you have a very easy way/procedure to return your Mac to its former working state.