Joined a new workplace. Lead wants me to research on the available list of certain frameworks.

But they have already built a couple of services using certain frameworks and they don't seem to be having any issues with them.

I asked why look for new ones when you already have stuff that work for you and they're like "It's working - is not a reason to not look for new ones".

I mean WTF? Isn't "Don't try to fix things that are not broken" literally the point?

Since it's tagged with web dev - when something is working without issues, it's outdated and has to be replaced.

The company wouldn't get capable web devs otherwise since nobody would sign up with a company that uses an ancient, two months old tech stack.

To be fair, you can interpret that as "It's working, but our experience with it is not one we wish to repeat", or it can be a mean of preventing the job from becoming stale and to keep up with advances in the field.
It's a riskier approach, but I think there's also value in it.
Also, though it might not apply much to your team if innovation is bounded to the use of new tools, but if we were always saying "but it works now, why change it?", we wouldn't progress much as a species. And even if your team solely strives to be early adopters of new technologies, this role is needed for innovations to start impacting the world.

@CptFox By "It's working", I meant - we didn't have any problems with it so far and it is good enough for our use-case.

There are several other tech debts to address. For example: This company has been around for 30 years and they don't have a single line of documentation. Can you imagine going to your senior every single time you have a question only to find out that the senior has been around only for the past 5 yrs, but the project is 10 yrs old?

Someone gives a task that will help you to learn, you instantly question their judgement. What is the problem?