Oracle Forms, in my opinion, not too much. I started doing Oracle Forms in 1998, but it had really dropped off by about 10 years later when web became common. There may still be legacy apps running there though, for instance I believe a military business had some very high security data which was viewable only in Forms. For use cases like that often people are slow to re-platform! At one point all the UK natural gas metering went through Oracle Forms, I worked on the original and upgraded systems and around 8 years ago this was still the case.

Oracle apex is still used though because if you have an Oracle DB it's such an easy way to build a website over it. It's way easier than Rails or Django, but it can also be enhanced pretty much like a normal web app, it's all restful etc. I know a couple of people who've been working full time on it for decades now,

Curious to understand the reason of not choosing a modern UI and backend using Open Source tech stack such as React/Java/Golang/PostgreSQL ?

Software development and continuous maintenance costs money and not every company has any business trying to run a software development department.

Every company should be focused on data analytics though

Especially writing a bespoke data entry system.

You can find plenty of cheap good enough consulting companies that can make modifications to any of the third party SaaS products.

Understood. It is no doubt the maintenance and the time to build. However, it does take some efforts to build Oracle forms that requires a good amount of development time in PL/SQL and for customization of forms screens.

The thing is that it is a well understood platform and easy to hire out one of the major consulting companies by giving them the requirements and signing a statement of work.

Then when you don’t want to deal with them, hire out another one.