Users often turn to web apps that allow them to view Instagram users' profile pictures in full size for several reasons:

1. Enhanced Viewing Experience: Instagram's native interface limits the size of profile pictures, often displaying them in small thumbnails. By using a web app, users can view the profile pictures in their original, high-resolution size, allowing for a more detailed and immersive viewing experience.

2. Curiosity and Interest: People may be curious to see a profile picture in full size to get a closer look at the details, such as the quality of the image, the subject, or any unique features. This can be especially relevant for public figures, celebrities, or individuals with captivating profile pictures.

3. Profile Analysis: Viewing profile pictures in full size can be useful for analyzing the aesthetics, branding, or personal style of an Instagram user. This can be beneficial for businesses or influencers seeking inspiration or conducting competitor research.

4. Social Media Research: Researchers, marketers, or social media enthusiasts may use web apps to access full-size profile pictures as part of their analysis or data collection. This can provide insights into user demographics, trends, or patterns across different profiles.

5. Profile Verification: In certain cases, users may want to verify the authenticity of an Instagram profile by examining the profile picture in full size. This can help determine if the profile belongs to a real person or if it might be a fake or impersonation account.

6. Artistic or Creative Inspiration: Artists, photographers, or designers may find inspiration in Instagram profile pictures. Viewing them in full size allows for a closer examination of composition, color palettes, or other artistic elements that can spark creativity.

7. Personal Interest: Users may simply have a personal interest in viewing profile pictures in full size, whether it's to admire the photography skills of an Instagrammer, appreciate the beauty of nature captured in a picture, or explore the visual aesthetics of different profiles.

It's important to note that using web apps to view Instagram profile pictures in full size may have limitations or be subject to privacy concerns. Users should exercise caution, respect others' privacy, and ensure they are using reputable and secure platforms to access such content.