You do not have to tip every single time. But it allows a means to tip, without setting a monthly obligation, like Patreon.
I still plan to set up a Patreon account, but I intend to keep this option open for folks who want to casually support my work without having to make a long term commitment.
I have done some reading and thinking on the subject. There are inherent problems with micropayments that I don't think will ever be resolved with regards to paying the cost of moving the money. I don't think that surcharge will ever get so low that it is viable to leave a nickel or a dime. At best, it might be possible to arrange a prefunded wallet with a service and leave a nickel, but I am not sure if that is viable or even what the point is.
If you feel (for example) that my writing is worth a nickel a page, leave a dollar for every 20th article. It isn't a big thing.
Paying the content creator directly is a much more efficient means of supporting content creation than ads or product sales. While I do have ads on some of my sites (but not on all of them) and while I am still exploring products, like t-shirts and what not, if you spend $20 on a t-shirt, the content creator gets a small cut of that. It puts much more money into their pocket to just tip them $5. So, unless you seriously value that t-shirt and want it in specific, it just makes a lot more sense to tip than to expect content creators to also put time and energy into figuring out product design on top of writing/comicking/whatever.
Frankly, if they are good at creating t-shirts, they can make money at that without necessarily writing. They can do a Zazzle shop or an Etsy shop or whatever. Those folks aren't really in the business of content creation. And it is fine if they like making t-shirts and stuff, but if you really want good content online, it just makes more sense to me for people to tip and pay for the content directly.