What does it matter how many people think these platforms are useless? Even if 7 billion think they're useless, that leaves them with quite enough of a market segment.
A quick search shows that Zapier has over 3M users and IFTTT has 18M users, so they got that going for them.
IFTTT recently introduced a pro pack which quite heavily impacts a large portion of its userbase, which is why I personally think that their current number of users is pretty useless as a metric.
They also charge services for supporting them and want the services to make a special API for them (as opposed to plugging into existing ones), which is why I find them relatively scummy.
That being said, Zapier is just expensive. From my memory it's like $20/month if you want more than 3 automations running, and can easily rise to $50/month. I like it as a service, but that price is fairly unreachable for me.
I've only just found it but try out Integromat. So far it feels like the middle ground between IFTTT and Zapier in terms of features and price.
It also handles processing earlier data which won me over. Want GitHub tasks to get into your Todoist workflow? Easy enough to do on all 3 for future issues.
Integromat lets you process issues that already exist.
A quick search shows that Zapier has over 3M users and IFTTT has 18M users, so they got that going for them.