Yes. There are various kinds of disabilities that prevent people with disabilities from effectively accessing internet. Utopian.io also has certain issues in this respect.
Using Tab appears to have no effect. Let me show this clearly with a pic.
I tapped on tab button of my keyboard various times and as you can see on the bottom left the curson went to write blog option. But the visual cue (like a select box) was missing to indicate a person that he has reached the particular option.
Ability to navigate a website through only keyboard is important for people who may have motor issues and cannot handle a mouse !!
Below is the data from a study which indicates the types of disabilities faced by international students (who arrive in US).
Source
Show a rectangle with solid borders to indicate where the cursor or selected option is:
In this day and age, accessibility is the cornerstone of modern web development. Utopian.io cannot succeed in its mission without managing the accessibility concerns of the general populace. It is infact a necessity, and not a choice.
Last but not the least, we must show that we care by having concerns for people who may not be as physically endowed as most of the population.
