This comes off a bit presumptuous. I would assume that they are aware this is a possibility.
"having to use a web service to view you stack trace"
This is just not a downside that matters for this usage scenario. It's almost the same story as minifying your frontend JS bundle, uploading source maps to Sentry, then using Sentry to view an unminified stack trace from a user's browser. The user was never going to view that stack trace anyway, and I am not bothered by having to use Sentry to view it - I never would have seen it at all otherwise.