TLDR: No.

Imagine it is 2521 CE. Someone asks "Did 21st century people struggle to read computer files the way they do today? Is it a problem to do with degradation, or did they use obscure formats to hide their ideas?"

The answer is much the same. THE STANDARD FORMATS CHANGED every hundred years or so.

Handwriting styles changed, even the shape of the letters changed - a lot. Look at Latin handwriting from 300CE, then 600, then c800, etc - totally different. I can read anything from c500-c1500, then c1800-today, but pre-c500 and c1500-c1800, yeah, it's a nightmare. But at the time it was standard (more or less) - people wrote to be understood. There were regional differences throughout - you can look at a medieval or renaissance manuscript and make a fairly good guess at which region it was written in.

Charlemagne standardised handwriting across his empire, and the letters took on the shapes ("caroline minuscule" which he believed to be derived from the best form of Classical lettering) more-or-less as they are today. But then of course regional differences crept in again.

I admit I'm not sure why it got so suddenly different c1550. There was a fairly huge increase in written documentation around then, and "secretary hands" were developed (again, very different from country to country) that unlike "book hands" were very fas to write. The faster the more scruffy. Scribes had used abbreviations since forever, but again these were often regional or language-dependent. There are whole fat books of medieval abbreviations, for example.

So in short, their contemporaries would have not have had such a problem. But vecause fashions change, and because reading requires practice before your brain recognises the shape of words , we struggle (for many words the brain doesn't really read every letter but recognises the general shape of the word, which is why slabs of UPPERCASE ARE MUCH HARDER TO READ QUICKLY).