It’s understandable, to a degree at least. After all, the whole purpose of a website is to promote you, your business, or to showcase your service, so shouldn’t you have complete control over what the user experiences? If that includes resizing their browser window or pumping your favorite tune the whole time the site is up, so be it! Right?
The short answer is no, but since this is a blog and not a facebook post, allow me to elaborate. Forcing the browser window to resize and/or adding background music (especially if there is no way to mute it) may seem like a cool, unique way to customize the experience of visiting your site. However, doing so is pretty much the online equivalent to TV commercials that jack up their volume to stand out from regular programming. They’re more likely to make a potential client exclaim, “Argh, this is ANNOYING!” than “What a captivating user experience!” Now are there exceptions to this rule of internet etiquette? Well, yes and no.
Yes, if your website is music related in some way, and having the user rock out to some sweet jams while they browse your site makes sense. Examples include musician websites or sites that are in some way music related (such as a music festival, music school, or if your beer is named after a musical genre). Please note that even in these cases, you should always include a visible music player with a pause/play button.
No, however, if you think it’s a good idea to force the browser to resize. EVER. I (and most web users) would rather visit an ugly site that maintains my browser dimensions than a beautiful site that takes my Firefox session, with its many many open tabs, and squishes it down to one website’s “optimal viewing size”. It just follows common courtesy: You don’t cut people off in traffic, you don’t talk to them with food in your mouth, and you don’t mess with their browser!