When it comes to gaining muscles & losing fat there's no genetics excuse that prevents you from doing it, atleast not until you reach your maximal potential.
Yes - there are always going to be the outlyers or the so called "genetically gifted", onto whom models won't necessarily apply, but chances are neither me or you are one of those.
In the 'Social Media realm' we live in, perhaps, I feel like the standards are set too high for various reasons, and false expectations tend to contribute on making beginners of the more unhappy of their results. Therefore here are two models from two of the leading minds of the industry, on what's achievable - following the right nutritional strategies & training.
These can help give us a very good understanding of the diminish in return we get from training, and what it actually take (in terms of time spent training over the years) to forge a strong and muscular body.
From the get go, we can see that most gains are made within the first 2-3 years: from there it gets much more difficult to keep progressing. You still can, it just becomes almost unnoticeable on a month to month/year-to-year basis.
Also, the conditions mentioned take into account the right strength training program based on progressive overload with the proper nutrition (caloric surplus to maximize gains). Continuously, for years, and we know that's not the case when it comes to trainees,
Each end every year, the growth potential diminishes up to a ~50% until the 4th year, point from which it becomes way more difficult to progress, and where weight gain becomes veery, very small.