I totally appreciate where you're at right now because I heard a lot of the same things when I was starting my career and it was confusing to me too. The whole catch-22 of "you need experience to get experience" is so frustrating especially when you're starting out.

The way agencies work isn't rocket science, but there are specific systems that are pretty consistent across most agencies and in a lot of creative and marketing departments for different kinds of businesses. I think what people are saying when they say "we want agency experience" even when they're hiring for a junior role, is that they want somebody who knows the system, who knows how agencies work, how “we” work. They want somebody who can do the creative work, knows how the creative process unfolds within an agency, and how to work with all the people involved.

Creative agencies generally have these three departments. There are other people in other roles at agencies, but this is the foundation of most agencies and a lot of other businesses that do creative as well:

1. The creative department. That's you guys, the designers, art directors, copywriters, creative directors, and so on.
2. The account services department. These are the people that liaise with the clients, that have those back and forths about process and manage the client relationships.
3. The project managers. They write the timeline and keep everything running and everybody on track, sometimes they also work on the budget.

A lot of other creative departments that are client-side or in-house (like banks and retail companies and tech companies) are filled with people who have worked at agencies, and those people have brought the systems that they know from those agencies to these other internal departments, ‘cause the system works well there too.

So what someone's saying when you don't have agency experience is that they can't see that you've worked in a similar structure before. They can’t see from your resume or interview that you know how to collaborate with people in other roles in an agency, or have an understanding of what everybody does, or how the system works. This is likely a problem for them because they need their new hire to just come in and do the work without any training or managerial oversight.

The fact that if you have no agency experience and they're still interviewing you anyway, after seeing your resume with presumably no agencies on it, means that they like your work enough that they’re probably open to you having earned this experience elsewhere. So my advice to you is to talk in interviews about how you have worked with other people in the past. That can be classmates and teachers if you’re just out of school. Or if you've only had retail, food service jobs, or similar, talk about how you work with your colleagues. How you communicate with your boss, any external vendors, delivery, garbage takeout, whatever. Anybody that you've ever had to communicate information with and do some kind of collaborative work or task with professionally. That'll speak to how you can work with other people and that'll address the heart of their question about how much agency experience you have.